California: Former US president Ronald Reagan personally apologized to Margaret Thatcher when US troops in 1983 secretly invaded Grenada, a Commonwealth island state in the Caribbean, according to newly-released tapes.

The US president apologized for any "embarrassment" caused to the British premier, who was not informed in advance about the mission to topple the island state`s Marxist government.

Britain`s Queen Elizabeth II is the head of the Commonwealth, a grouping of nations which includes several Caribbean island states such as Grenada.

"We regret very much the embarrassment that`s been caused to you," the US leader said during the call in which the famously close leaders referred to each other by their first names.

"If I were there, Margaret I`d throw my hat in the door before I came in," he said to Thatcher, using an old US saying based on a visitor throwing his hat inside a home in case he was unwelcome and it was thrown out.

"There`s no need for that," Thatcher replied in the 10-minute conversation.

The conversation was disclosed in archive tapes released by the Ronald Reagan Presidential Library in Simi Valley, California.

The call was apparently made as the military invasion was still underway. "We think that the military part of it is going to end very shortly," Reagan said at one point.

Explaining the need for utmost secrecy about the 1983 operation, Reagan said they were concerned about Cuban authorities getting wind of the invasion plan.

"We were greatly concerned because of a problem here ... we`ve had a nagging problem of a loose source, a leak here," he said.

There were some Cuban military forces on the island who did battle with the invading US forces during several days of heavy fighting.

The US invaded Grenada as part of its Cold War fight against the spread of Communism around the world.

The invasion was launched after a revolt within the Marxist government that Washington said put US students on the island in danger. A western-friendly leader was installed after the US victory.

The Reagan conversation ended on a cordial, and upbeat note.

Thatcher asked after Reagan`s wife Nancy, saying "Give her my love" -- and then said she had to get back to a "tricky" House of Commons debate.

"Go get `em. Eat `em alive," said the US president as the pair signed off.