(theguardian) -- The US president said he did not want to come if there were large-scale protests and his remarks in effect put the visit on hold for some time.

The call was made in recent weeks, according to a Downing Street adviser who was in the room. The statement surprised May, according to those present.

The conversation in part explains why there has been little public discussion about a visit.

May invited Trump to Britain seven days after his inauguration when she became the first foreign leader to visit him in the White House. She told a joint press conference she had extended an invitation from the Queen to Trump and his wife Melania to make a state visit later in the year and was “delighted that the president has accepted that invitation”.

Many senior diplomats, including Lord Ricketts, the former national security adviser, said the invitation was premature, but impossible to rescind once made.

Trump has named Woody Johnson, a Republican donor and owner of the New York Jets, as the new ambassador to the UK but has yet to nominate him formally. A large number of US ambassadorial positions remain unfilled worldwide largely due to the Trump team failing to make any formal nominations.

The acting US ambassador to the UK, Lewis Lukens, a career diplomat, clashed with Trump last week by praising Sadiq Khan, the London mayor, for his strong leadership over the London Bridge and Borough Market terror attack.

His remarks came just days after Trump criticised Khan for his response to the attack, misquoting the mayor’s message to Londoners not to be alarmed by the increased presence of armed police.

Khan’s office pointed out Trump’s error later but the president responded by accusing London’s mayor of making a “pathetic excuse”. Khan then called on the UK government to cancel Trump’s invitation. No date had been fixed for the visit.

The UK’s traditional effort to act as a bridge between the US and Europe has become more complex since the vote last year to leave the European Union and Trump’s support for policies that have angered European allies.