Theresa May has forced the Queen into a “very difficult position” by inviting Donald Trump to the UK on a state visit, a former head of the Foreign Office has warned.
Lord Ricketts, who led the department between 2006 and 2010 questioned whether the new US president was "specially deserving of this exceptional honour".
Trump sparked global outrage after he signed an executive order to ban people from seven majority Muslim countries from entering the US for 90 days.
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A petition calling for the trip to be cancelled has attracted more than 1.5 million signatures, but May has held firm, insisting the invitation for an unspecified date later this year still stands.
In a letter to The Times, Lord Ricketts – who now works as an adviser to defence firm Lockheed Martin and a non-executive director at energy company Engie – said it was unprecedented for a US president to be invited to Britain for a state visit in their first year in the job.
"Most have had to wait till their third," he wrote. "Is Trump specially deserving of this exceptional honour? It would have been far wiser to wait to see what sort of president he would turn out to be before advising the Queen to invite him.
"Now the Queen is put in a very difficult position. The government needs to move fast to protect Her Majesty from the growing controversy, as shown by the overwhelming response to the petition."
Ricketts urges Downing Street to instead tell the White House that a full-blown state visit "will take place later in the presidency", and suggests that a lower-key official visit should take place before Britain rolls out the red carpet.
"Not an easy manoeuvre, but the consequence of having rushed to premature invitation for political effect," he adds.
"Divisive and wrong"
Foreign secretary Boris Johnson told MPs yesterday that due to the "energetic actions" of ministers, no British passport-holders would be affected by Trump's executive order.
While he repeated that the measure was "divisive and wrong", Johnson would not go further in his criticism, and instead stressed the importance of the US-UK relationship.
A visibly angry Yvette Cooper, who chairs parliament's Home Affairs Committee as well as a taskforce on refugees, urged Mr Johnson to show "guts" and speak out against the other recent order from Trump to suspend the admission of refugees into the US.
"This is not just about the impact of British citizens, one of our closest allies has chosen to ban refugees and target Muslims and all he can say is 'well, it wouldn't be our policy' - that is not good enough," she said.
More than 70 MPs last night unanimously backed a motion in the Commons condemning Trump's ban.