I had time to gaze at the Earth and listen to opera

Dennis Tito

But he also used the event to rebut claims made by the US space agency (Nasa) that he was hindering the crew's work.

"There's absolutely no way that my presence can interfere with their work," Mr Tito said in the audio and video link-up with mission control outside Moscow. He said he was helping the ISS crew by carrying out "menial tasks", such as serving up food.

Dennis Tito took off on board a Soyuz rocket on Saturday

The 60-year-old businessman said he had greatly enjoyed taking pictures and listening to music on his CD player. "I had time to gaze at the Earth and listen to opera," Mr Tito said. And he said he was "amazed by the size and the accomplishment" of the space station.

Mr Tito paid Russia some $20m (�14m) to travel to the ISS. He arrived on Monday and is due to return to Earth aboard a Soyuz craft this weekend.

Mr Tito revealed that he had slept well on the two-day journey up. "In weightlessness, one can sleep like a baby," he said.

However, according to the American space agency, Mr Tito's presence on the ISS is causing stress at Nasa.

In weightlessness, one can sleep like a baby

Dennis Tito

"The current situation has put an incredible stress on the men and women of Nasa," Dan Goldin told a US House of Representatives panel on space and aeronautics on Wednesday.

"Mr Tito does not realise the efforts of thousands of people, in the United States and Russia, who are working to protect his safety and the safety of everyone else."

But Mr Tito said he had spent most of his time in an area of the ISS more than 100 metres (328 ft) away from the US segment of the ship, and that his presence did not hinder the work of the crew. He also denied reports that his movements on the ISS were being monitored.