ROBIN COOK rode to the defence of his diplomats yesterday and emphatically denied claims that they were involved in ''any kind of conspiracy'' to ship arms to mercenaries in West Africa.

The Foreign Secretary insisted neither he nor his Ministers had seen any documents that suggested the security consultants Sandline International were about to break the United Nations arms embargo on Sierra Leone.

Using a series of carefully worded denials, Mr Cook launched a robust defence of his department's handling of the row, which has further damaged his political credibility. There were no senior Cabinet Ministers on the front bench beside him to lend support.

His move came just 24 hours after Tony Blair signalled his frustration at the way the affair has spun out of the Government's control. On Monday he praised the British High Commissioner to Sierra Leone Peter Penfold for his ''superb'' work in helping restore democracy to the country.

Mr Cook dismissed as ''wild allegations'' Sandline's claims that Foreign Office officials had approved the company's plans to restore British-backed President Ahmad Tejan Kabbah earlier this year after he was deposed by a coup. ''I have more faith in my officials than I have in Sandline,'' he said.

He faced a barrage of criticisms from Tories led by his foreign affairs Shadow Michael Howard, who branded the affair a ''shambles'' and said Mr Cook's department was ''wholly out of ministerial control''.

Mr Cook's statement was seen at Westminster as a belated attempt to support his officials in public after he appeared last week to be blaming diplomats for failing to keep him aware of developments in Sierra Leone.

He told MPs: ''In all the papers on this affair, I have found no evidence that officials in the Africa Department were involved in any kind of conspiracy with Sandline, or gave any prior approval to a breach of the arms embargo.''

He threatened to sue a Tory MP who suggested his statement could be interpreted as an improper attempt to intervene in the official Customs and Excise investigation into the Sandline affair.

Mr Cook, who faced repeated barracking from Opposition MPs, was forced to answer an emergency Tory question in the Commons. With Labour MPs packed into the benches behind him, he defended the ''positive outcome'' of the events in Sierra Leone, which ''represented the restoration of the legitimate and democratic government in place of the military regime''.

His argument was bolstered by a four-page letter from President Kabbah who said Britain had not been involved in any arms shipments and who played down Sandline's role in his return to power. But the British-based company, led by former Scots Guards Lieutenant Colonel Tim Spicer, hit back by issuing a statement claiming it had been heavily involved in the fighting in Sierra Leone.

Stung by Tory claims that the arms-to-Africa affair is the equivalent of the arms to Iraq scandal that undermined the last government, Mr Cook said: ''Sierra Leone is no Iraq. In Iraq a brutal dictator is still in power and still producing artillery shells on machine tools exported to him with the full connivance of the Conservative Party.''

He faced a vigorous challenge by Mr Howard, but the Tory front bencher had his credibility as a prosecutor undermined by Mr Cook, who reminded him he had suffered 13 defeats in the courts when he was Home Secretary in the last government.

His threat to sue came against Reigate Tory MP, Crispin Blunt - former special adviser to former Foreign Secretary Sir Malcolm Rifkind.

Mr Blunt asked whether it was coincidence that on April 29, the day after Mr Cook became aware of the letter from Sandline's solicitors, Customs and Excise officials delayed indefinitely an arranged interview with Sandline head Lieutenant Colonel Spicer.

Mr Cook said: ''If you repeat outside this house any suggestion that I have improperly intervened in the Customs investigation, I shall sue, because it is completely untrue.''

Last night, Sandline issued a cautiously-worded statement which suggested it is no longer prepared to engage in a war of words with Mr Cook. It said: ''Lieutenant Colonel Tim Spicer and his colleagues at Sandline International are cooperating fully with the officers of HM Customs and Excise having conduct of the inquiry and look forward, with equanimity, to their conclusion as to the facts.''

Meanwhile, Liberal Democrat leader Paddy Ashdown - himself a former diplomat - hinted in a speech in Strasbourg that he believed the ends justified the means in Sierra Leone.

He said he was in favour of the restoration of an elected government and added: ''It is a murky old business, foreign affairs and intelligence, I have no doubt about that and sometimes you have to achieve good things by less than perfect means. I am not going to start getting prissy about this.''

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