ROBIN Cook pinned his political future to the arms-to-Africa affair yesterday, promising he will resign if the inquiry into Britain's links with international mercenaries proves he misled Parliament.

The Foreign Secretary denied reports that the Government knew about the counter-coup in Sierra Leone organised earlier this year by the British-based private security company Sandline.

However, with Opposition MPs seeking to drag the Prime Minister into the row, Mr Cook was forced to clear his diary and spend the day in London tackling the latest crisis to engulf his tenure as Foreign Secretary.

He appealed for justice for the civil servants implicated in allegations that Sandline informed the Government of its plans to ship arms to Sierra Leone as part of its successful operation to restore the regime of President Kabbah.

He denied claims that his junior Minister Tony Lloyd had offered to quit for his part in the saga after he admitted failing to give full information to the Commons Foreign Affairs Select Committee.

He also rejected suggestions that Defence Secretary George Robertson and Armed Forces Minister John Reid had known about the operation.

Mr Cook has ordered an independent inquiry into the affair, which will follow the outcome of an ongoing Customs and Excise criminal investigation.

''If Ministers are found to have been at error, if they have knowingly misled the House of Commons or if they have adopted the wrong policy, then they must take the consequences,'' Mr Cook told BBC's Breakfast with Frost.

''I accept that, but I know I have nothing to hide. That is one of the reasons why I am very keen that this should be a full and open investigation so that the public can see exactly that.''

On the key point - whether Ministers knew about British involvement in the overthrow of the Sierra Leone junta - Mr Cook was adamant: ''The fact of the matter is there was no Ministerial approval for the activities of Sandline. There is no record, no evidence of any Ministerial discussion with Sandline. There has been no Ministerial involvement with Sandline.''

Mr Cook expressed concern that newspapers were treating as fact what he insisted were merely allegations against civil servants, but confirmed that the Foreign Office had hired top lawyers to defend its officials.

Sources close to Mr Cook dismissed claims that he is ''at war'' with senior officials in his department, and that he was forced to overrule their demands that the inquiry be conducted by diplomats instead of an outsider.

The row has its roots in a February arms shipment to Sierra Leone, organised by Sandline, to help the ousted democratically-elected regime return to power after a military coup.

Customs and Excise launched an investigation into the affair, prompting Sandline to release a letter to Ministers detailing extensive contacts with civil servants it says prove the British Government was aware to the scheme.

Asked about claims that Royal Navy engineers helped mercenaries repair a helicopter involved in the overthrow of the junta, Mr Cook said HMS Cornwall went to Sierra Leone at a late stage in the restoration to power of President Kabbah.

Photographs showing British personnel attending a Sandline helicopter did not show British military involvement, Mr Cook said. The helicopter was there to provide humanitarian assistance.

Asked about his suggestion, while in opposition, that it was wrong for civil servants to have to resign and for Ministers to abdicate responsibility when things went wrong, Mr Cook said he stood by those comments..

''I totally stand by my policy and accept responsibility for my policy,'' he said.

''The point I have been making repeatedly is there was no policy to support any mercenary involvement to overturn the junta in Sierra Leone.''

Mr Cook's intervention failed to satisfy the Tories, who claimed the Foreign office had run a coup in Sierra Leone without telling its Ministers.

Shadow Foreign Secretary Michael Howard said: ''The key question is did Ministers know what was going on and if not, why not?''

He accused Mr Cook of not spending enough time studying the documents submitted to him by his officials. ''Is the real truth that Robin Cook - as he boasted just a few weeks ago - failed to finish the paperwork? Is this mess the price we are paying for the idleness of Robin Cook.''

Liberal Democrat foreign affairs spokesman Menzies Campbell called for the scope of the independent inquiry to be extended to other departments, including the MoD.

Meanwhile, Tory leader William Hague called on the Prime Minister to step in and clear up the mess.

''We will need to know from the Prime Minister what on earth is going on in his Government, at the Foreign Office and the Ministry of Defence,'' he said.

Mr Cook's predecessor as Foreign Secretary, Sir Malcolm Rifkind, joined in the criticism.

The president of the Scottish Conservative Party and former Cabinet Minister said that he found it hard to believe that Mr Cook did not know that British mercenaries were behind the coup.

''I frankly find it difficult to believe that his own diplomats would actually be pursuing a course that involved breaking UN sanctions and assisting in the overthrow of a government without even telling their Ministers,'' he said.

''We have an extraordinary situation here because the question is: who's in charge of the Foreign Office? ''Is it the Foreign Secretary or the diplomats that he is supposed to be the boss of?''

Sir Malcolm said he was staggered by the allegations and was demanding to know how big a part officials had played in the scandal.