JUST WHEN they thought its was safe to go into the Olympics some of the world's top athletes have been issued with a shark-attack warning.

Triathlon is scheduled to make its debut as an Olympic event in 2000, but there are concerns for the competitors' safety following an attack on a rower in Sydney Harbour earlier this week near to where they are to due to swim.

Andree Mocsari was tossed from her boat after a shark bit into it, 200 metres from where the race starts and finishes at the Sydney Opera House. As a precaution, Australian officials have cancelled the New South Wales State Triathlon Cup which was due to be held tomorrow.

"If there is a trend here, then obviously we'll have to reconsider our whole strategy for the Olympics," said Tim Wilson, the executive director of Triathlon Australia.

It could mean that the triathlon, already one of the most physically and mentally demanding athletic tests ever devised, involving a 1500-metre swim, a 40-kilometre bike race and a 10-kilometre run, is about to get even tougher. "I guess it should speed up the swim anyway, joked one local triathlete.

Among the favourites for the Olympic gold medal in Sydney are expected to be: Britain's Simon Lessing, the world champion, and Spencer Smith, his predecessor. The course has earned widespread praise from competitors and television executives who are impressed with the breathtaking backdrop.

It is believed cleaner water in the harbour over the last few months has attracted more fish and, with them, more sharks. It is triathlon's second shark scare this week. A four-foot shark was spotted in the water at Glenelg Beach in Adelaide on Sunday at another race, but was warded off by officials.

John Smallwood, the president of Triathlon NSW, said his organisation had cancelled their race on the advice of the Maritime Services Board and NSW Water Police.

"We don't wish to be alarmist and we recognise the risk of attack is very small," he said.