Labour has roundly rejected accusations of “anti-Semitism” against Jeremy Corbyn by a man claiming to be his former adviser, saying the accuser never even worked for the party.

It follows an article in The Sunday Times by Harry Fletcher, who was referred to as “a media and strategy adviser to [Labour leader] Jeremy Corbyn from 2015-16”.

However, Labour said Fletcher had been “sourced from another political party” as fodder for “an attack story”.

Only days after Prime Minister Theresa May announced a general election, Fletcher said Corbyn was “anti-Semitic along the institutionalised lines of the Metropolitan police in the 1990s, when they messed up the Stephen Lawrence investigation”.

The Conservative MP for Finchley and Golders Green has said it was “disturbing” and showed that the Labour leader was not fit to lead the country.

However Labour tweeted: “Sunday times attack story from a source from another political party who never worked for Labour. Not serious.”