Apart from Melandri, who was taken off the Montmelo track on a stretcher, Loris Capirossi and Sete Gibernau were also being examined by medical staff and then taken to hospital.

The other riders involved in the incident at the start of Sunday's race, which was brought to a halt after the first lap, were Dani Pedrosa, Randy de Puniet and a Suzuki rider.

The race was restarted about half an hour afterwards but without Melandri, championship leader Capirossi and Gibernau, who appeared to cause the fall.

Australia's Casey Stoner, who got the best start each time, led the race till he fell on the eighth lap. On the previous lap, Japan's Shinya Nakano was shown the black flag and excluded, and France's Randy de Puniet fell to end his race.

By the 10th lap, there were only 11 riders on the track following yet another fall by Spain's Dani Pedrosa.

Rossi however moved up the field throughout the race. He started in pole position and was in fourth spot for the first few laps before moving into third on lap six and then into second spot on the eighth circuit.

When Stoner fell, seven-time world champion Rossi moved into first place and bit by bit shook off Americans Nicky Hayden, Kenny Roberts Jr, John Hopkins and Colin Edwards.

It was Rossi's third win this season.

Italy's Andrea Dovizioso won the 250cc race and Spain's Alvaro Bautista won the 125cc category.