The Tory treasurer, who lives in America, was thinking of buying into the island's sugar business at the time, in 1994. Then, Cuban sugar was sold mainly to the Soviet Union, but the industry suffered after the latter's collapse and the billionaire abandoned his plans.
If Mr Ashcroft had been an American he would have been barred from business with Cuba under US law, but he is a citizen of the United Kingdom, Belize and the Turks and Caicos.
Mr Ashcroft, whose main home is in Florida, took the four MPs - Sir Tom Arnold, Jacques Arnold, Andrew Rowe and Richard Tracey - to Cuba, Panama and the Turks and Caicos. Sir Tom Arnold left and the other MPs went on to Belize.
Mr Rowe, member for Faversham and Mid-Kent and the only one still an MP, said the trip changed his view of the American trade embargo. "We talked to Cubans and it became perfectly clear that if the Americans lifted the sanctions the vast majority of people would much prefer to do trade with the US," he said.
Jacques Arnold, who lost his Gravesham seat at the 1997 general election, said he had an interest in Latin America. Mr Ashcroft had showed the MPs a rice mill on Grand Turk and an orange-juice processing plant in Belize whose product was exported to the US, Mr Arnold said. He was hoping to set up a project in Cuba, possibly growing and processing sugar cane.
Mr Arnold said he had long been an opponent of the American trade sanctions on Cuba and spoke several times on the subject in the Commons.
Yesterday, Jack Straw, the Home Secretary, confirmed a report in The Independent last week that Mr Ashcroft, a tax exile, could be banned from making big donations under a shake-up of party funding to be unveiled tomorrow.
Mr Straw told Peter Sissons on BBC TV's Breakfast with Frost programme that foreigners living abroad who had "no connection" with Britain should be banned from donating but government plans were "not directed at individuals".
Mr Ashcroft has said it was "appalling" that The Times newspaper had omitted a paragraph from a letter to it by David Mackilligin, Britain's former High Commissioner in Belize, backing a Tory inquiry into claims that he used his links with the previous Tory government to protect his financial interests in Belize.
The crucial paragraph said "access should not be confused with the wielding of improper influence. I never received any evidence whatsoever that there was any of the latter".Reuse content