Almost 1,000 Labour supporters have signed an open letter suggesting that Monday’s protest against antisemitism in the party was the work of a “very powerful special interest group”.

The letter, addressed to Labour leader Jeremy Corbyn and uploaded to the We Support Jeremy Corbyn Facebook group, also accused organisers of using “immense strength” and “employing the full might of the BBC”.

The Jewish Leadership Council (JLC) and the Board of Deputies coordinated the rally, in Parliament Square, before delivering a letter to a meeting of the Parliamentary Labour Party (PLP).

The open letter adds that the “special interest group” attempted to use their “history and influence” to dictate how the country at large will vote, the Independent reported.

By this morning, almost 1,000 people had commented under the post to ask for their names to be added, while more than 2,000 had “liked” the post.

Lord Finkelstein, the Conservative peer and Times columnist, tweeted: “This is truly, truly amazing. These people are arguing that the Jews use our influence, power and media control to conspire to make - and here comes the hilarious bit - a FALSE argument that they are antisemitic! The sheer stupidity is staggering even before you get to the racism.”

In the wake of Monday’s protest, the government is expected to announce a parliamentary debate on antisemitism today, to be heard after the Easter recess.

Sam Coates, the deputy political editor of the Times, tweeted: “NEW: Theresa May seeking to capitalise on Labour woes: Govt are going to announce at the business statement a general debate on anti-semitism on Tues 17 April.”

Today is the last day before Parliament’s Easter recess, with MPs and peers returning on April 16.