Keir Starmer should not retaliate if Donald Trump hits the UK with trade tariffs, the former chancellor Jeremy Hunt has said, with ministers braced for the president’s latest round of economic measures.

The former chancellor told the Guardian the UK did not have enough economic firepower to start a trade war with the US, hours after Trump began one with China.

The president imposed a 10% tariff on Chinese goods on Tuesday and says he intends to impose 25% tariffs on Canada and Mexico. Beijing responded with its own tariffs on American fossil fuels and agricultural machinery, but British officials have not confirmed whether they would respond in a similar way if Trump turns his attention to imports from the UK.

Speaking to the Guardian’s Politics Weekly podcast, Hunt said: “The reason that you generally hit back with retaliatory tariffs – which is what China, America, Canada and Mexico are all in the process of doing, or threatening to do – is to give you leverage so that the other side then wants to remove the tariffs that they’ve introduced.

“But our … goods exports to the United States account for less than 0.5% of US GDP. So we should be very realistic, we don’t have any leverage when it comes to that.”

He added: “We are a country that has always flourished on the back of free trade. [We were the] first country in the world to unilaterally remove our [trade] borders back in 1846. [A trade war] is bad for British manufacturers who use a lot of imported materials and it’s bad for inflation. We should stay out of these trade wars.”

Trump’s tariff move on Tuesday marked the first phase of a global trade war, in which the UK’s position remains unclear. He said this week that Britain was “out of line” with its trade policies, but added: “I’m sure that one, I think that one, can be worked out.”

Trump also spoke warmly about his relationship with the prime minister, sparking hope in Whitehall that the UK could avoid the tariffs being imposed on China and threatened against Canada and Mexico. Starmer is hoping to persuade Trump not to impose tariffs on Britain by using US trade data which shows the US ran a trade surplus with the UK in 2023, rather than British figures that show the reverse.

But ministers are aware the president could include the UK in the trade war at any moment, and have been meeting for weeks to discuss their response should this happen. During Trump’s first term, the UK was hit by US tariffs on the EU as a whole, and responded by imposing its own on American exports of whiskey, blue jeans and motorbikes.

This time, however, Brexit has given Britain the chance to avoid being caught up in a US-European trade war, and to set its own tariff policy outside the European customs union.

Hunt’s comments will put pressure on his party leader, Kemi Badenoch, to back the government should it decide not to retaliate in any US trade war. Despite her previous role as business and trade secretary, Badenoch has said little about how she would respond in the event of a trade dispute with Washington, although she has urged the government to pursue a broader trade agreement with the US.

Hunt said he thought the Tory leader was doing the right thing by not announcing policies so early in her leadership, though he urged her to resist the temptation to lead the Tories to the right in an effort to capture Reform votes.

“The right approach is not to copy them, because our coalition of voters will always be a different coalition of voters to Reform,” he said. “There are lots of reform voters who will never vote Conservative … So I think we have to be completely realistic about that.”