Friends and colleagues have paid tribute to double America's Cup winner Sir Peter Blake, who was killed by pirates in the Amazon.

Hampshire-based Sir Peter, 53, was travelling with nine others aboard the schooner Seamaster in the Amazon and was yesterday about to set sail for the River Orinoco when masked gunmen struck.

Business partner Alan Sefton, a neighbour of Sir Peter and his family in Emsworth, said: "He was in Macapa, on the north side of the mouth of the Amazon, clearing customs and immigration before leaving Brazilian waters."

He said the crew had returned to the yacht when they were attacked, adding: "A band of seven or eight hooded people with guns just appeared out of the blackness.

"We believe Sir Peter was below or had gone below because he became aware of what was happening - he rushed up to find out what was taking place, was confronted by one of the gunmen and was gunned down in his tracks."

Mr Sefton said that Sir Peter had been killed instantly after being shot twice. The gunmen fled, taking only small items such as watches and cameras, shooting behind them.

Two other people on board were injured but had later returned to the yacht after hospital treatment.

New Zealand-born Sir Peter was knighted in 1995. He had also won the prestigious Whitbread Round the World Race in 1989 and the Jules Verne Trophy in 1994.

In July, the United Nations environment Programme appointed him a goodwill ambassador.

He had lived in Britain since the 1970s, splitting his time between there and his native New Zealand.

Together with Mr Sefton and another partner, Scott Chapman, he had started a company to raise the profile of environmental issues.

Mr Sefton said: "Blake Expeditions was Peter's ultimate dream, his final and greatest achievement."

He said that Sir Peter had started to be concerned about mankind's impact on the environment during his trips sailing the world and had wanted to raise awareness through expeditions and documentaries.

Paying tribute to his friend, Mr Sefton said that Sir Peter had been a committed and passionate person, with a great sense of humour, who would be sorely missed, particularly by his wife Pippa and two teenage children.

He added: "It seems ironic - Peter has been through the Southern Ocean eight or nine times, the Antarctic and next year was planning to sail the North West Passage.

"He had spent two months on the Amazon and had only met beautiful, warm people and yet after all that, it was when he got back in to so-called civilisation that something this terrible happened."

Bruno Trouble, organiser of the America's Cup and a friend of Sir Peter's, said: "He went through life like lightning.

"Peter was an extraordinary leader of men . . . he had an amazing charisma. I think that he was actually hiding his shyness."