Marlena Shaw, whose hits include 'Woman of the Ghetto' and 'California Soul, ' and who featured on a recent Coca Cola ad campaign, received her money only after strong assurances were given to the Americans that the nightclub had no connection with the Castro government.

The problem came to light following Shaw's three-date Irish tour, when her agent complained that she had not been paid the agreed performance fees.

When Allied Irish Bank was asked to enquire what had happened to the cash transfers sent two weeks previously, it was discovered that payment had been blocked in the US.

An email sent to AIB from a US financial institution stated:

"This transaction cannot be applied due to the reference to Cuba. This reference is similar to an entity related to sanctions against the country of Cuba as provided by the US treasury office of foreign assets control."

Declan Forde, of PoD Concerts, which promoted Shaw's gigs, said: "It seems the mere mention of the word Cuba was enough to trigger alarm bells in the US treasury's system so the transaction was automatically halted and the money transferred into what they called a 'blocked account'. We or Marlena Shaw's management were not notified of this. The reason only became apparent when our bank enquired."

He added: "We have booked US artists into Cuba in Galway for many years now and the problem had never arisen before but it's good to see the US government is maintaining the moral high ground on human rights and I'm sure the residents of Guantanamo Bay in Cuba are grateful to them for that."

Donal Ward, of Cuba nightclub, said: "The payment was to have been made prior to the performance and the problem could have led to the show being cancelled. However, it was only about a week after that we were notified there was a problem and that the transfer had been blocked. The reference in the transfer was clearly to Cuba, Galway and clearly indicated it was a music venue in Ireland."

He added: "We always make clear in transactions that this is a venue in Galway and nothing to do with politics. This follows a previous problem around 2000 when a band called Pucho and his Latin Soul Brothers played. Then a US money transfer was stopped but that time the reference was to 'Pucho's money for Cuba'."

Cuba opened in 1998 as a Latin-themed bar with Salsa dancing, serving cocktails and cigars. When the nightclub opened, this theme was extended to pictures of Che Guevara, Cuba flags and murals of Castro adorning the walls.

Noel Carrillo, the Cuban ambassador to Ireland, while amused by the Shaw incident, said that it illustrated how problematic the US blockade was for Cuban society. "The question of the blockade is not well understood in the world, " he said.

"The American government is trying to confuse the issue by calling it the embargo. It reality it is an attempt to asphyxiate our country. It has an extra-territorial character, which means that according to America legalisation, US subsidiaries anywhere in the world cannot trade with Cuba. Foreign enterprises investing in Cuba face threats from the American government, such as not giving visas to their managers and saying they may consider them as trading with an enemy of the US."

He added: "More recently, the Bush administration has been tightening the financial blockade, confiscating money that may be connected to Cuba.

They've now established a committee at the treasury department whose only purpose is to follow every single small transaction that may involve Cuba.

That is why they know even if a single person has visited Ireland that may be connected with Cuba and they follow it."

The United States embargo against Cuba, known as 'el bloqueo' by the Cubans, was imposed in 1962. It restricts all economic, commercial and financial transactions between the countries to those deemed by the US government to be humanitarian in purpose. The United Nations voted for an end to the blockade against Cuba in 2003 and again in 2005. Only four nations . . . the US, Israel, the Marshall Islands and Palau . . . opposed the motion.