Thousands of members who quit the Labour Party did not do so because of Jeremy Corbyn’s response to the Salisbury nerve agent attack and his handling of allegations of antisemitism, party officials have insisted.

A leaked report suggests 17,000 people have left the party since the start of the year – amounting to 3 per cent of the total membership.

Hundreds have quit over the crisis engulfing the party and many more have not renewed their direct debits, according to internal figures seen by The Times.

However, Labour sources insisted the drop was not related to Mr Corbyn’s recent controversies. The party gives members six months to pay membership arrears, meaning the majority of those whose subscriptions lapsed in the past few months actually stopped paying fees last year.

They said that the leaked data does not include last week, when the latest row about antisemitism in Labour erupted, and is in keeping with other equivalent periods.

A spokesperson said: “Labour’s membership is well over half a million and in fine health. The latest data has been misrepresented in this story.”

Labour’s membership reached a peak of 570,000 after the general election but now appears to be falling.

According to the leaked report, no region in England reported a rise in party members since the start of 2018. London lost 3,500 members in the past three months, and the North-west reported a fall of 2,000.

Meanwhile the Corbyn-supporting campaign group Momentum has claimed that it is gaining members.

The latest row erupted after it emerged Mr Corbyn had previously objected to the removal of an east London mural that depicted wealthy Jews playing Monopoly on the backs of workers.

Facing mounting criticism over his response, the Labour leader admitted there were “pockets” of antisemitism in the party and apologised for the “pain and hurt” caused to Jewish people.

Mr Corbyn’s close ally, Christine Shawcroft, was forced to resign from the party’s National Executive Committee after it emerged she had defended a council candidate accused of Holocaust denial.

In an attempt to defuse the crisis, the Labour leader’s Facebook account was deleted this weekend following claims senior staff working for Mr Corbyn were members of groups that contained antisemitic comments.