Sir Keir Starmer and Donald Trump have agreed the relationship between the UK and US is "incredibly strong" and will "continue to thrive", Downing Street has said.
In the first phone call between the pair after the US election, the PM offered his "hearty congratulations" to Trump after his "historic victory" and said he looked forward to working closely with the President-elect, a No 10 spokeswoman said.
It comes after Kemi Badenoch urged Sir Keir to apologise for "derogatory" comments made about Trump by David Lammy before he was foreign secretary.
In her first appearance in Parliament as Conservative leader, she pressed Sir Keir on how Trump's election would affect UK policies on trade and defence.
Badenoch asked the prime minister if he would push for Trump to get an invitation to address Parliament, but did not receive a direct reply.
In their phone call, Downing Street said the pair also discussed the situation in the Middle East and the PM "underscored the importance of regional stability".
"The leaders fondly recalled their meeting in September, and President-elect Trump’s close connections and affinity to the United Kingdom and looked forward to working with one another," a spokeswoman added.
Sir Keir and his foreign secretary held a dinner with Trump in New York in September, when the pair met for the first time.
In opposition, Lammy labelled Trump a "neo-Nazi sympathising sociopath" but since getting into government has sought to build bridges with the president-elect and his team.
Earlier, the PM's spokeswoman was pressed on whether Lammy would keep his job for the entire Parliament in light of his past comments, and replied: "Yes, he is the foreign secretary."
During Prime Minister's Questions, Badenoch said the US was the UK's single biggest trade partner and warned the prime minister he would need to "look after the special relationship".
She said there was now a "risk of increased tariffs on UK exports" and asked if he would revisit talks on establishing a free trade agreement with the US.
Since leaving the European Union, UK ministers have been keen to reach a trade deal with the US - however, there has been little progress.
During his election campaign, Trump pledged to dramatically increase tariffs on foreign exports.
Replying to Badenoch, Sir Keir said: "Of course we will discuss issues of our economy with the president-elect, as we already have done."
Later, Chancellor Rachel Reeves told MPs on the cross-party Treasury Select Committee the UK's trading relationship with the US was "crucial", but she was "confident those trade flows will continue under President Trump".
She added: "[He's] been President before, we continue to have a good and strong economic relationship... I’m optimistic about our ability to shape the global economic agenda."
On defence, Badenoch echoed calls from Trump that European countries should increase their defence spending and urged the prime minister to match her party's commitment to raise defence spending to 2.5% of GDP by 2030.
Sir Keir reiterated his government's commitment to the 2.5% target - although it has not set a deadline for meeting the goal.
He added that, unlike the previous Labour government, the Conservatives had failed to meet the target while in office.
He also attacked the Conservatives for leaving a £17bn black hole in the Ministry of Defence's finances.
Labour accused Badenoch of misleading Parliament when she incorrectly told MPs that the “chancellor's Budget did not even mention defence”.
Badenoch's spokesman insisted she had not got it wrong because it was "obvious" from the context of what she had said in her previous question that “she was referring to the fact that there was no reference to how Labour intend to get to that 2.5%”.
In her Budget speech last week, the chancellor said “we will set a path to spending 2.5% of GDP on defence at a future fiscal event.”
'Roll out the red carpet'
Trump's election victory has divided UK politicians.
Scottish First Minister John Swinney said Scotland and the US "share many social, cultural and economic links".
"In that relationship, we will stand fast in support of our values of fairness, democracy and equality – ideals that America was built upon."
Badenoch said: "The world faces many serious challenges and I look forward to our two countries working together to confront them."
Nigel Farage, Reform UK leader and a friend of Trump, said the president-elect was a "genuine friend of the United Kingdom" and urged the prime minister to "roll out the red carpet" for him.
"This is a huge opportunity to be grasped."
'Dark day'
Other UK party leaders have been more critical. Lib Dem leader Sir Ed Davey called the election result "a dark, dark day for people around the globe".
"The world’s largest economy and most powerful military will be led by a dangerous, destructive demagogue.
"Fixing the UK’s broken relationship with the EU is even more urgent than before - we must strengthen trade and defence cooperation across Europe to help protect ourselves from the damage Trump will do."
Green Party co-leader Carla Denyer called Trump "a dangerous bigot, bully, and liar".
"On this dark day, we stand in solidarity with all US citizens who fear a convicted criminal and a fascist in the White House."
And Labour London Mayor Sadiq Khan, who has repeatedly clashed with Trump, said many Londoners would feel "anxious" and "fearful" about what the outcome of the election would mean for democracy, women's rights, the Middle East, Ukraine or tackling the climate crisis.
