The BBC has been ordered to stop paying senior Labour MP Diane Abbott thousands of pounds in fees for appearances on a late-night politics programme.
In a landmark ruling, the corporation has been found to have breached its own guidelines in the way it employs the shadow health minister on the BBC1 show This Week.
The corporation?s Editorial Standards Committee, part of the BBC Trust, has upheld a complaint concerning more than ?6,500 of payments to Miss Abbott since her promotion to the Labour front bench in October 2010.
Ruling: The BBC has been ordered to stop paying senior Labour MP Diane Abbott (right) thousands of pounds to appear with Andrew Neil (centre) and Michael Portillo on politics show This Week
The ruling is likely to have wide-ranging consequences for the BBC and its political coverage.
It could see a cap on appearances by high-profile politicians such as London Mayor Boris Johnson, former Home Secretary Alan Johnson and former Liberal Democrat leader Charles Kennedy.
It may also limit the number of senior politicians appearing on popular shows such as Have I Got News For You.
The standards committee?s findings, seen by the Daily Mail, are critical of the makers of This Week, saying that ?Abbott?s appearances on the programme since becoming a shadow minister had been too frequent?.
The committee added that paying Miss Abbott, who earned between ?839 and ?869 per edition, ?such substantial appearance fees since she took up her front bench position in 2010 was a breach of the guidelines?.
The complaint dates back to January when crossbench peer Lord Laird wrote to BBC Director-General Mark Thompson arguing it was wrong that, as a shadow minister, Miss Abbott should ?profit financially? via the BBC licence fee for expressing political opinions and discussing Labour policy as a pundit on the programme, hosted by Andrew Neil.
Party stalwart: Diane Abbott MP addresses delegates on the third day of the Labour Party conference in 2010
In his letter Lord Laird quoted from BBC guidelines which state: ?We should not normally pay MPs, or others clearly identified as representing political parties, for appearances or other contributions to any BBC output in which they are speaking as a member of their party or expressing political views.?
Mr Thompson responded by saying that the guidelines did not apply in Miss Abbott?s case because This Week is ?not a traditional political programme?.
But Lord Laird appealed and was told the Editorial Standards Committee, which comprises five members of the BBC Trust, would examine the matter.
Its findings, due to be published today, criticise the amount Miss Abbott earned and say that in future she should only be paid a ?realistic disturbance fee? as an occasional pundit on This Week alongside regular contributor and ex-Tory MP Michael Portillo.
The report also notes that Miss Abbott?s appearances on This Week ?should have been limited to once or twice a year? since becoming a shadow minister. The programme?s executive editor, Robbie Gibb, has agreed to this.
Lord Laird said: ?I am delighted the BBC Trust has made the BBC admit that its own very clear rules were not being enforced. Mark Thompson tried to fob me off but the Trust has proved he was wrong to do this.?
Miss Abbott was not available for comment last night. But a spokesman said she had given up her regular appearances on This Week since her front bench appointment and now appears only ?occasionally?.