In an apparent contradiction to the UK Government's position, the US Embassy had issued an 'Urgent Notice' on its website.
It had told UK citizens who share dual nationality with one of seven mainly-Muslim countries covered by the restrictions not to apply for visas, meaning individuals such as Tory MP Nadhim Zahawi could yet be affected.
But the 'Urgent Notice' was later deleted with the US Embassy not commenting on whether it will be replaced with new advice.
Donald Trump's ban WILL apply to British citizens, the US embassy said
The notice had stated: "Per U.S. Presidential Executive Order signed on January 27, 2017, visa issuance to aliens from the countries of Iraq, Iran, Libya, Somalia, Sudan, Syria and Yemen has been suspended effective immediately until further notification.
"If you are a national, or dual national, of one of these countries, please do not schedule a visa appointment or pay any visa fees at this time.
"If you already have an appointment scheduled, please DO NOT ATTEND your appointment as we will not be able to proceed with your visa interview.
"Please note that certain travel for official governmental purposes, related to official business at or on behalf of designated international organizations, on behalf of the North Atlantic Treaty Organization, or by certain officials is not subject to this suspension."
We will not be able to proceed with your visa interview.
Last night, the Foreign Office had insisted British dual nationals would not be affected by the ban after Foreign Secretary Boris Johnson won assurances in a phone call with President Trump's son-in-law Jared Kushner yesterday.
A Foreign Office source told Express.co.uk they still believed British nationals were exempt from the visa ban and were working to clarify the US Embassy's new advice, which they expect to be changed.
They said: "The Foreign Secretary’s statement yesterday is based on the clarification he was given by the White House on what the order means for UK nationals.”
It was suggested the contradiction could be due to confusion among American officials over the implementation of President Trump's executive order.
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Donald Trump's Action Plan
Thu, January 19, 2017
What follows is Donald Trump's action plan to 'Make America Great Again' within the first 100 days of Presidency.
1 of 10
FIRST: Propose a Constitutional Amendment to impose term limits on all members of Congress.
The Foreign Office's official travel advice currently states: "Temporary immigration measures are in place affecting British nationals who hold dual nationality with Libya, Iran, Iraq, Somalia, Sudan, Syria and Yemen."
But in a statement issued last night, the Foreign Office said: "The Foreign Secretary Boris Johnson has today held conversations with the US government and as a result we can clarify that the Presidential executive order only applies to individuals travelling from one of the seven named countries.
"If you are travelling to the US from anywhere other than one of those countries (for instance, the UK) the executive order does not apply to you and you will experience no extra checks regardless of your nationality or your place of birth.
"If you are a UK national who happens to be travelling from one of those countries to the US, then the order does not apply to you – even if you were born in one of those countries.
"If you are a dual citizen of one of those countries travelling to the US from OUTSIDE those countries then the order does not apply to you.
"The only dual nationals who might have extra checks are those coming from one of the 7 countries themselves – for example a UK-Libya dual national coming from Libya to the US.
"The US has reaffirmed its strong commitment to the expeditious processing of all travellers from the United Kingdom."
The notice was later deleted
More than one million Britons have signed a petition calling for President Trump's state visit to the UK to be cancelled following the introduction of his ban.
Mr Johnson is due to make a statement to MPs this afternoon.