HONG KONG, June 27 (Reuter) - Tibetan activists in Hong Kong challenged Beijing on Friday by flying the Tibetan flag and calling for the Himalayan region's independence in a defiant protest days before Hong Kong reverts to Chinese rule.

A small group of protesters from the Free Tibet movement demonstrated outside Hong Kong's parliament in Statue Square.

One protester, Dorji Dolma, sat on the edge of a Tibetan flag. She sat Buddha-like but with her mouth gagged in a gesture representing what the activists regard as Communist-ruled China's repression of the Tibetan nation.

It will probably be the last time that demonstrators fly the Tibetan flag in Hong Kong with impunity.

The British-ruled territory reverts to China's sovereignty next Monday night after 156 years of British colonial sway.

The new authorities to be installed by China plan to ban the advocacy of independence for Hong Kong, Taiwan or Tibet. Beijing views all three as inalienable Chinese territory.

Tibet has been in China's firm grip since Chinese troops suppressed a fierce insurrection by Tibetans in 1959.

Taiwan is the last bastion of the former Chinese Nationalist government which fled to the island after losing the civil war to the Communists on the mainland in 1949.

Organisers said Friday's demonstration was likely to be the last legal one here calling for Tibetan independence.

The protest was organised by campaigners from Australia and Britain. "This banner is the Tibetan flag, and the display of this flag is forbidden in Tibet, and we're convinced it's going to be forbidden in Hong Kong after 1st July," said Alison Reynolds, director of the London-based Free Tibet campaign.

Hong Kong's future leader Tung Chee-hwa has said any calls for Tibetan independence will be illegal after the handover.

"So we thought it was very important we came to Hong Kong to warn people here about freedom of expression and restrictions that are going to be imposed on them, and also to make a final call for Tibetan freedom before it became illegal," Reynolds told reporters.

Beijing has made clear it will not tolerate Hong Kong becoming a base for subverting China.

At China's behest, Tung is introducing curbs on civil and political liberties so that protests which threaten China's "national security" will be disallowed.

Asked if the Tibetan activists were not rocking the boat by staging the protest in Hong Kong just four days before the handover, Reynolds said.

"Well, we've come from overseas to make this call for independence. We're aware that Tibet is a very sensitive issue here, and we're also aware that people may not want to speak out publicly about it.

"But we feel it's important to do so, and that's why we've come. But freedom of speech, freedom of expression... is our other message here today."

The group said there were "chilling similarities" between how China plans to take control of Hong Kong and its military "occupation" of Tibet.

"The people of Hong Kong, like the people of Tibet before them, face absorption into mainland China without an act of self-determination or consultation," it said in a statement.

Although there is scant outward similarity between the bustling, capitalist territory and the impoverished Himalayan region, the group said Hong Kong and Tibet had both been promised autonomy from Beijing.

But the group said that if Tibet's experience was any guide, the "one country, two systems" pledge for Hong Kong may be "nothing more than a polite fiction that belies the deprivation of human rights and increased military controls."