Cabinet minister Harriet Harman will face questions in the Commons this morning over what she knew about an illegal donation to her campaign for deputy leader.

As Leader of the House, she will make a statement about forthcoming business and take questions from MPs.

She was expected to appear yesterday in her role as minister for women during a debate on rape law but did not do so.

More than £650,000 of donations from controversial businessman David Abrahams to the Labour party were not lawfully declared.

Mr Abrahams used four associates to donate money over four years. Giving money under someone else’s name is unlawful.

Ms Harman accepted £5,000 from Janet Kidd but it has emerged the money was actually from Mr Abrahams.

She won the Labour deputy leadership in June and was made Secretary of State for Equality, chair of the Labour party and Leader of the House.

Her husband, Jack Dromey, is Treasurer of the Labour party and he is under pressure over what he knew and when.

The party’s general secretary resigned earlier this week after it emerged he had known about the illegal donations for some time.

Ms Harman has been publicly backed by the Prime Minister, but the pressure on her and Mr Dromey to explain what they knew and when is increasing.

Yesterday the party’s chief fundraiser, Jon Mendelsohn, admitted he was told about the disguised donations last month.

One of Ms Harman’s rivals for the deputy role, Hilary Benn, was offered £5,000 through an associate of Mr Abrahams but refused.

He was later given money directly by Mr Abrahams, which he accepted.

Former Cabinet minister Baroness Jay appears to have known about the disguised donations, as she advised the Benn campaign not to accept donation offered through an Abrahams associate.

Gordon Brown turned down donations to his leadership campaign from associates of Mr Abrahams.

Ms Harman sat beside Mr Brown at Prime Minister’s Questions yesterday.

Acting Lib Dem leader Vince Cable mocked the “remarkable transformation in the last few weeks from Stalin to Mr Bean, creating chaos out of order rather than order out of chaos.”

Tory leader David Cameron said:

“We have had 155 days of this government, disaster after disaster, a run on a bank, half the country’s details lost in the post and now this. The Prime Minister’s excuses go from incompetence to complacency and there are questions about his integrity. Are not people rightly asking, “Is this man simply not cut out for the job?””

Mr Brown replied:

“I hope that there will be all-party support so that everything in party politics is above board, including the use of third party sources for donations.

“As for competence, I remind the right hon. Gentleman that in 1992, he sat there when interest rates reached 15 per cent. Competence is the lowest interest rates for a generation, the lowest inflation for a generation, the highest employment for a generation, doubling investment in the health service, a minimum wage and properly financing education. We will continue to do our best by the country.”