Trevor Phillips has called on the three Labour leadership candidates to pick a side as senior party figures on Monday condemned the decision to suspend him over alleged Islamophobia.

Throwing down the gauntlet to Sir Keir Starmer, the favourite to succeed Jeremy Corbyn, the former chairman of the UK’s equalities watchdog told The Telegraph his case was a “test for the kind of party these candidates want to lead.”

His calls were echoed by a number of Labour moderates, who criticised the failure of Sir Keir, Lisa Nandy and Rebecca Long-Bailey to denounce the decision to suspend one of the country’s most prominent anti-racism campaigners.

In a warning shot to the candidates, Lord Mann, the Government’s anti-Semitism tsar, said: “It is a mark of leadership...either back the investigation or back Trevor Phillips.

“To suspend the first head of the Equality and Human Rights Commission is not a sit on the fence issue.”

It came as Jennie Formby, Labour’s general secretary, faced a major backlash on Monday over the decision to suspend Mr Phillips over a series of remarks dating back several years.

Lord Falconer, Labour’s former Lord Chancellor, accused Ms Formby of acting swiftly to sanction critics of Mr Corbyn while allowing number of high-profile anti-Semitism cases to drag on for many months.

He highlighted the expulsion of Alastair Campbell, Tony Blair’s former press secretary, who was last year expelled after admitting that he voted for the Liberal Democrats in the Europeans elections.