Senior Labour peers have offered to investigate allegations of anti-Semitism in the party, as they warned Jeremy Corbyn that without full openness it is “a cancer that will continue to grow”.

Baroness Smith of Basildon, the shadow leader of the Lords, was among signatories to a letter to Mr Corbyn in which the Labour Peers Group offered to establish a small panel to review the substance of allegations made in last week’s Panorama programme.

The group’s chairman Lord Harris of Haringey, shadow deputy leader of the Lords Baroness Hayter of Kentish Town, and shadow chief whip Lord McAvoy also signed the letter.

They suggested they draw upon the trade union, legal and other experiences of the group to “provide advice and support on how a properly independent complaints process could be set up and run”.

And the peers offered to use the group’s corporate governance experience to “propose how the party’s governance arrangements can be improved”.

They wrote: “The purpose of these proposals is to ensure that the Labour Party can regain the trust of its members, supporters and the wider public.

“As the leader of our Party you have a responsibility to ensure that we do this.

“In particular, you need to demonstrate decisive leadership that Labour is determined and committed to do everything possible to remove anti-Semitism, and those that defend it, from our Party.

“Without full openness, this is a cancer that will continue to grow and, in hurting us, it will most hurt those that need a Labour Government. We are prepared to do all we can to assist.”

The Panorama programme claimed that senior figures, including Jeremy Corbyn’s communications chief Seumas Milne and general secretary Jennie Formby, had interfered in anti-Semitism investigations.

Labour has denied the claims and written a complaint to the BBC.

The shadow cabinet is expected to meet on Monday to discuss anti-Semitism, a source told PA.

Mr Corbyn is due to address the Parliamentary Labour Party after the special meeting.

Meanwhile, the Guardian reported that more than 200 former and current Labour staffers have written to Mr Corbyn asking for more support for whistleblowers.

And it said Labour staffers in the GMB union have submitted a motion for discussion at their branch meeting which calls for an apology for the party’s response.

Mr Corbyn is understood to have spoken to staff at the party’s headquarters in central London on Monday.