Although he did not name Mr Ashcroft in speech to the United Nations in New York, the Deputy Prime Minister's fierce criticisms will add to the controversy surrounding William Hague's money man, who lives in Florida for much of the year.
Mr Ashcroft, 52, who is said to be Britain's 24th richest person and has made big donations to Tory coffers, holds joint British and Belizean nationality. His company, Belize International Services is controller of the Belize shipping register.
The 911 vessels on it, which fly the Belize flag but are owned by many countries, are on average 27 years old. Increasingly they are being criticised for slack safety standards and, more recently, pirate fishing activities. By being on the Belize register they escape supervision and control.
At a meeting yesterday of the UN's Commission on Sustainable Development, its principal environmental policy-making forum, Mr Prescott said Belize- registered vessels had the worst record in Europe, America and Canada for ships detained as unseaworthy after inspections by port officials.
And he referred to a new report by the International Transport Workers' Federation (ITF) and Greenpeace, which says that Belize-registered vessels are now some of the worst offenders in illegal fishing in the Antarctic. "These modern-day buccaneers must not be allowed to plunder our seas for profit at the direct expense of seafarers' lives, and of the environment," he said.
Mr Prescott, himself a former merchant seaman, told UN delegates in New York: "All my life as a seafarer and a politician, I have campaigned against the abuse of flags of convenience, which have costthousands of seafarers' lives."
Their use was now affecting the environment as well, he said, adding: "I particularly deplore the reckless illegal fishing under flags of convenience that we have seen threatening the stocks of toothfish in the Antarctic, with consequences for birdlife, including the wandering albatross."
Belize-registered trawlers have been blamed for illegal overfishing of the Patagonian toothfish, an important species which some experts fear may be being driven to extinction.
Last night Greenpeace and the ITF sent a letter to Mr Hague urging him to raise with Mr Ashcroft the issue of the "shoddy operation" of the Belize shipping register which, they said, had already cost lives. Mr Ashcroft should ensure that the register complies with international law, they said.
Simon Reddy, Greenpeace's oceans political adviser, said last night: "It is simply not acceptable that such a senior figure in a major British political party should be presiding over a shipping register which is clearly abusing international obligations on safety and the environment.
"We call on Mr Hague to bring Mr Ashcroft into line."Reuse content