Rachel Reeves has delivered a thinly-veiled warning to Donald Trump about his plans for the US economy.
The president-elect has spoken about his intention to impose import tariffs on all foreign goods entering America.
That has sparked fears of a global trade war as Trump seeks to boost American manufacturing by pursuing a more isolationist agenda.
But in her first Mansion House speech as chancellor on Thursday night, Reeves called for “free and open trade” between the UK and other countries - and specifically name-checked the US.
She said: “I will always do what is in our national interest, for our economy, for our businesses and for the British people.
“That means free and open trade, especially with our most economically important partners. This includes the United States, our single most important destination for financial services trade.
“There is so much potential for us to deepen our economic relationship on areas such as emerging technologies.
“I look forward to working closely with president-elect Trump and his team to strengthen our relationship in the years ahead.”
Any hit to trade between the UK and America would be a major blow to Labour’s number one mission of boosting economic growth.
The scale of the challenge facing Reeves was highlighted on Friday morning by new data which showed the British economy only grew by 0.1% between July and September.