SYDNEY - AUSTRALIAN police have been given extra powers for the Olympic torch relay through Canberra to ensure planned demonstrations do not become violent, officials said on Wednesday.

Thousands of Chinese supporters are planning to welcome the Olympic flame to the Australian capital, raising concerns over potential clashes with Tibetan groups protesting Beijing's treatment of their people.

Police will be given extra powers to search demonstrators for potentially dangerous items such as guns, knives and smoke bombs during the torch's April 23-24 Canberra stop, the Australian Capital Territory (ACT) government said.

The territory's chief minister Jon Stanhope said the enhanced security powers were introduced because of the threat of clashes between opposing demonstrators.

'A group of China supporters have proposed to come to Canberra to...express their support for China, and a similar number of protesters or demonstrators have proposed to express their dissent about human rights,' he said.

'It's in the context of a potential for a clash between two competing groups of demonstrators or protesters that the police have asked for these additional powers,' he told national radio.

The Olympic torch has been beset by demonstrations over China's crackdown on protesters in Tibet since it was lit at Olympia in Greece on March 24.

In angry scenes in London and Paris, demonstrators tried to extinguish the flame, prevent torch-bearers from participating in the relay and scuffled with police. - AFP