Syria has declared the UK's ambassador persona non grata in a symbolic rebuke.
Simon Collis, who left the troubled country in March, and the US, French and Turkish representatives were among those told they are no longer welcome.
The move by Bashar Assad's regime comes after the countries expelled more than a dozen senior Syrian diplomats in protest at the massacre of scores of people in the Houla area of Homs.
A Foreign Office spokeswoman said: "We announced the expulsion of Syria's charge d'affaires - Syria's most senior diplomat in the United Kingdom - and two other diplomats from the embassy on May 29.
"The action was a direct response to the horrific killing of over 100 people including 49 children and 34 women in Houla.
"The UK has taken this action in concert with partners across the world sending a stark signal to president Assad and those around him that their actions have consequences and that they cannot act with impunity.
"It was also an expression of the international outrage at the Syrian regime's repression of its people, which continues even after the international community and United Nations Security Council's condemnation.
"The Syrian government's decision today appears to be a reciprocal gesture.
"The UK Government has already withdrawn all diplomatic staff from Syria on March 1, 2012."