The British Foreign Secretary, Mr Robin Cook, last night announced an independent inquiry into claims that British officials approved the illegal supply of arms used to overthrow the government of Sierra Leone.
In an emergency commons statement, he told MPs: "There will be no whitewash."
Earlier, the Prime Minister, Mr Blair, warned that if any minister or official was found to have deliberately breached UN sanctions banning the sale of weapons to the west African state, disciplinary action would follow.
Mr Cook said it was "unsatisfactory" that ministers had not been told that Customs and Excise were investigating Sandline International, the firm of military consultants said to have supplied the equipment.
He said the Foreign Office asked Customs on March 10th to investigate claims by the Liberal Democrat peer, Lord Avebury, that Sandline had arranged for weapons to be flown from Bulgaria to forces loyal to the deposed President Ahmad Tejan Kabbah.
However, officials failed to tell the Foreign Office Minister, Mr Tony Lloyd.
Earlier Sandline's solicitor, Mr Richard Slowe, issued a statement again insisting the firm, headed by a former British officer, Lieut-Col Tim Spicer, had been acting "with the approval of Her Majesty's Government".
Mr Cook said that although the allegations related to weapons said to have been supplied from Bulgaria, British law could have been breached if the sale was arranged in Britain.
A UN Security Council resolution imposing an arms embargo on Sierra Leone following the original overthrow of President Kabbah was incorporated into British law by an Order in Council.
President Kabbah was subsequently restored to power earlier this year.