Tory MP David Wilshire, a member of the committee: "He united the three parties"

Sir John Kerr, head of the diplomatic service at the Foreign Office, revealed that Baroness Symons had been briefed on the probe.

The foreign affairs select committee is investigating claims that British mercenary firm Sandline International supplied 30 tons of arms and ammunition to the troubled African nation during the coup.

"I misled MPs"

Sir John, permanent under-secretary at the Foreign Office, said the Foreign Office minister was briefed on March 10.

The same day, she addressed the Lords on the issue and two days later, minister Tony Lloyd made a statement in the Commons. Yet neither mentioned the investigation.

Baroness Symons denies deliberately misleading the Commons and says she will "correct any inaccurate statements" she made to the House.

The first time Sir John appeared before the committee, on May 14, he had told them he had briefed Mr Lloyd ahead of the debate.

He later retracted this evidence in a letter to the MPs, saying he had been mistaken. On Tuesday, he confirmed the error: "I misled the committee last time. I apologise. I went back and looked at the file and corrected myself."

Labour MP Ted Rowlands said he had been surprised on hearing, initially, that Mr Lloyd had been briefed.

"You have subsequently corrected that evidence," he continued, adding: "It is now clear the minister of state was not briefed."

Sir John said he had been correct when, on May 14, he made clear that Lady Symons had been provided with a briefing from officials and confirmed that "the papers had contained references to the fact that Sandline are being investigated for possible sanctions-busting".

Threatened with contempt

MPs on the committee threatened Sir John with contempt of Parliament for repeatedly refusing to answer their questions about who knew what.

He insisted from the outset of the hearing that his answers would cut across a formal independent inquiry by Sir Thomas Legg, who is hoping to publish his findings before the summer recess.

He was questioned about why Mr Lloyd did not see the papers that were shown to Baroness Symons.

"The papers will be provided for Sir Thomas Legg. I would be very happy to pursue the matter in the light of his inquiry. I would be unhappy to pursue the matter now," Sir John told the MPs.

"Non-answers unacceptable"

He repeatedly gave similar replies, adding that anything he said might also hinder disciplinary hearings.

He was accused of being evasive and was told it was unacceptable to give "non-answers".

Diane Abbott: "Stop trying to hide"

Labour's Diane Abbott said: "The committee is united in its admiration for you ... so you cannot hide behind Legg in discussion.

"We are simply seeking to establish matters of fact to pursue four lines of inquiry. You will do us a service if you cease to try and hide behind Legg.

"Drop this stuff about disciplinary hearings and answer our questions."

Tory Sir John Stanley, reading from the handbook of Commons procedure, warned that Sir John could be guilty of contempt.

"We trust that you will in answering the questions be giving answers to the questions and not seeking to hide behind the Legg inquiry," he said.

Robin Cook has repeatedly denied there was a cover-up.

He has pledged that he will resign as Foreign Secretary if the independent inquiry finds him culpable over claims that ministers knew of the shipment of arms to Sierra Leone to help the restoration of President Kabbah's civilian government.