It is billed as a cheap way to travel the world – staying for free in strangers’ homes in exchange for looking after their pets. But the world’s biggest housesitting company has been accused of encouraging its members to flout visa rules by providing misleading travel advice.

In some cases, members of TrustedHousesitters were detained and deported after arriving for international housesitting jobs without work visas, leaving them out of pocket and facing difficulties travelling in future.

TrustedHousesitters, which is based in the UK and was recently valued at £100m, charges housesitters £131 a year to use its platform. It lists thousands of opportunities to “stay for free with adorable animals in unique homes around the world”.

Advertised with the catchline “the freedom to travel”, it provides members with letters they can show immigration officers, suggesting that because housesits are not paid, they do not need a work visa.

The letters claim housesitters can travel to countries such as the UK, US, Australia and Canada as tourists or visitors, where they exchange “passionate pet care for free accommodation”.

But the Observer has spoken to TrustedHousesitters members who fell foul of immigration rules after arriving for international housesits as tourists – only to be told that it was unauthorised work.

While housesitting through TrustedHousesitters is not paid, housesitters receive payment in kind in the form of free accommodation. They provide a service that homeowners would otherwise need to pay for – often including pet care and chores like collecting post or watering plants.

TrustedHousesitters said it had been advised by immigration lawyers that its members were travelling for leisure purposes and not to work. It said only a “tiny handful” of its members had experienced problems, with data suggesting there were about 10 cases of border problems in 2023.

But housesitters prevented from entering the US and UK – the two most popular destinations – have accused the company of misleading members and “burying its head in the sand”.

Madolline Gourley, 34, from Brisbane, Australia, said she lost more than 5,000 Australian dollars (£2,584.50) after she was detained and deported while trying to transit through the US on her way to a catsitting job in Canada in 2022. Paperwork given to her by US immigration officials shows they considered her unpaid housesitting to be “unauthorised employment”.

“I can’t ever go back to the US as a tourist. I can’t even transit through the US any more,” said Gourley, who works in government communications.

She called it a “big red flag” in the company’s business model and is campaigning for UK regulators to intervene. “I have suffered serious consequences because I didn’t know I needed a work visa, but TrustedHousesitters are still allowed to operate and promote this like, ‘travel anywhere you want in the world with pets and a free place to stay!’. There are no consequences for the company, but there are plenty of consequences for the housesitter.”

In another case, Gemma Bailey, 45, from Hemel Hempstead, said she got a call from the UK Border Force telling her that her American housesitter had been stopped while trying to enter the UK. Bailey, a therapist, was due to fly to Bulgaria on holiday the next morning and had arranged for the housesitter to look after her cat.

“They said, ‘Have you got this lady coming to stay with you?’ and I said ‘yes’ and they said ‘why?’ and I said, ‘Because I’m going on holiday in the morning and she’s coming to look after my cat’,” Bailey said. “And they said, ‘Well no, she isn’t, because this isn’t legal.’

“They said she was going to be detained and they would make a decision about whether to deport her. They had fingerprinted her. She felt very aggrieved because she had been treated like a criminal.”

She added: “TrustedHousesitters need to accept that this is a legitimate issue and publicise it.”

TrustedHousesitters launched in 2010 and was acquired in December by London-based Mayfair Partners in a deal valuing it at £100m. This weekend, its website was listing 7,932 global housesitting opportunities. On Instagram, TrustedHousesitters has described petsitting as a “workation”.

Prof Michaela Benson, an expert in lifestyle migration at the University of Lancaster, said housesitting was a “grey area legally that needs to be addressed” and that the company’s marketing appeared to be “playing on the ambivalence of the situation”. “It is misleading and I think that people are right to be upset, given how that is presented,” she said.

TrustedHousesitters’ letters argue that unpaid housesitting is not a form of work so can be done by tourists or visitors. But the stance appears to contradict statements by UK and US government officials. A UK Home Office spokesperson said last year that it typically considers housesitting to be work, even if unpaid, and confirmed this position to the Observer. People trying to enter the US have been told by immigration officials that petsitting and housesitting in exchange for lodging is considered employment.

Nicolette Bostock, head of UK immigration at international law firm Withers, said that while rules varied, it was “highly likely” that many countries would consider unpaid housesitting to be work. “Even though there’s no money changing hands, it’s work,. It’s not for free – there is a transaction happening in that there is an expectation … between the housesitter and the house or pet owner, that defines what should be done, when and how, and what they get in exchange.”

She said: “The liability rests solely with the person seeking the entry … I would be wary of relying on those letters.”

Canadian housesitter Elyse Sevigny, 65, who showed a letter from TrustedHousesitters to border officials when attempting to travel to the US, said she felt it did “more harm than good”.

The nurse from Ottawa had been travelling for an unpaid dogsitting role in New Mexico in August 2023 when she was blocked from entering.

She said the immigration officer “came up with the clause that free housing is considered remuneration and therefore I was going into the US to work and I was not allowed entry. I was fingerprinted, photographed and given all this documentation. I was quite shaken up,” she said.

After contacting TrustedHousesitters, it refunded part of her membership fee.

In the TrustedHousesitters forum, which remains online, users encourage others to lie about their reasons for travel, and to say they are going to stay with a friend or family.

TrustedHousesitters is now facing scrutiny from UK trading standards officers, who are exploring potential breaches of the Consumer Protection from Unfair Trading Regulations.

Councillor Jacob Taylor, deputy leader of Brighton and Hove council, said it had received several complaints from overseas and was investigating. “We have also referred the case to the Competition and Markets Authority”

The CMA said it could not comment and TrustedHousesitters said it had “no record of any contact” from the authority. A spokesperson for the company said it regretted the challenges that “a handful” of its members had faced and provided support “when such rare instances occur”. It publishes guidance on its website which states that housesitters should verify all personal requirements before travelling and that its immigration letters “do not guarantee entry to a country”.

The spokesperson added: “TrustedHousesitters does not provide opportunities for work and has been consistently advised by international immigration lawyers that our members are travelling for leisure purposes, not work.”

Gourley, the Australian woman turned away at the US border, said: “I am shocked none of the government agencies are doing anything about it. The only ones penalised are the foreign travellers who don’t know any better.”