One of Britain’s largest care home chains, Care UK, has been sold to an American property investment company, the Guardian can reveal, in a deal that comes as private providers lobby the government for a greater role in the NHS.

Care UK, which operates more than 150 residential homes for older people, has been the subject of sale speculation since 2018.

The private equity firm Bridgepoint Advisers, which paid £420m for the company in 2010, had previously tried and failed to sell the chain, which employs about 10,500 staff and was founded in 1982. It said in its 2019 accounts that it had spent £2.5m on financial advice for an “abortive” sale process.

But Bridgepoint has now succeeded in selling the business to Welltower, a US real-estate investment trust (REIT) that specialises in care homes, according to Companies House filings.

Neither Bridgepoint nor Welltower appear to have announced the deal to shareholders and it is not yet clear how much the US firm paid.

But publicly available documents show that Care UK paid off a series of loans to HSBC shortly before the takeover took place. Care UK’s accounts show it had more than £300m in bank loans.

The deal comes as independent healthcare providers launched a charm offensive with the government, offering to provide their services to clear the NHS backlog.

In a letter to the Treasury, the Independent Healthcare Providers Network (IHPN), which represents private healthcare groups including Care UK, said its members could provide up to £1bn of capacity to help ease the crisis.

The health secretary, Wes Streeting, has previously said the Labour government would “go further than [Tony Blair’s] New Labour ever did” in making use of private health firms.

Care UK has invoiced central and local government for more than £840m of services since 2016, according to figures from the procurement data specialists Tussell. The business lost £2.6m last year on revenues of £490m, compared with a £4.4m profit in 2022.

Bridgepoint is listed on the London Stock Exchange but had not announced the sale to investors as of Friday afternoon. A notice officially announcing that Bridgepoint no longer had control of the company was posted on 16 October.

Three Welltower employees had already been installed as directors two weeks earlier, including the head of its London office, Jorge Charro.

The deal does not include Practice Plus Group, a leading provider of private hospitals and one of the largest NHS outsourcers. Bridgepoint separated the two businesses in 2019 and retains ownership of Practice Plus, which has won about £3.5bn of government contracts since 2012, according to Tussell.

The Guardian has approached Bridgepoint, Care UK and Welltower for comment.