WASHINGTON (REUTERS) - A bipartisan group of US lawmakers have nominated the Hong Kong pro-democracy movement for this year's Nobel Peace Prize.

Five senators and four House members said in letter to the chairwoman of the prize committee in Oslo the award would give voice to those fighting against the erosion of freedoms since Hong Kong was handed back to China from Britain in 1997.

"A number of democracy advocates are already in jail, some in exile, and many more awaiting trials where they are expected to be convicted and sentenced," a copy of the letter made available to Reuters said.

"This prize would honour their bravery and determination that have inspired the world," it said.

China imposed a sweeping national security law on Hong Kong last June after months of pro-democracy protests.

The law punishes anything China considers subversion, secession, terrorism or collusion with foreign forces with up to life in prison.

Critics say it is aimed at crushing dissent and it erodes freedoms in the semi-autonomous, Chinese-ruled city. Its supporters say it restores stability after months of unrest.

The winner of the prestigious Peace prize will be announced in October and the award presented in December.