COLOMBO (AFP) - Twenty-four elephants lined up for a race on Thursday on Sri Lanka's newest expressway, but thousands of spectators were left disappointed when organisers scrapped the event due to safety concerns.

The animals and jockeys were jostling at the start line on the Chinese-built 25.8km four-lane expressway from the airport to the capital when authorities had a sudden change of heart.

Police felt that the tuskers could pose a threat to the safety of spectators if one of them went out of control and the race was turned into a parade - to the disappointment of the crowds and the invited media.

"We did not expect this kind of crowd today," said provincial minister for transport and tourism, Nimal Lanza.

"We have over 100,000 people at the starting point and another 200,000 at two exits of the expressway."

The road, costing US$292 million (S$362 million), will cut travel time between the airport and the city by half to 20 minutes.

President Mahinda Rajapakse is set to ceremonially open it on Sunday.

Elephants are treated as sacred animals in Sri Lanka where they are paraded at Buddhist temple festivals and protected by law.