China's powerful People's Liberation Army, or PLA, staged a parade in Hong Kong Sunday, its first public display of military muscle since the former British colony was returned to Chinese rule in 1997.

At least 17,000 people in Hong Kong looked on as the PLA celebrated the 77th anniversary of the national army's creation.

Gripping their automatic weapons, 3,000 soldiers marched in lock step as military helicopters buzzed over the parade ground in a rural area of the territory.

Beijing says it hopes the event will strengthen ties between mainland China and Hong Kong.

But some analysts are saying the nationalistic display is meant to boost support for pro-Beijing politicians in the run-up to September's legislative elections.

The army is denying any political agenda. In comments made just before the parade began on Sunday, local PLA commander Wang Jitang praised Hong Kong's economic strength and promised to defend it.

Mr. Wang said his troops will help maintain Hong Kong's stability and keep the city safe.

The military display takes place with Hong Kong still stinging after China barred a series of democratic reforms in the territory in April. China's decision was followed by massive street protests in Hong Kong.

The central Chinese government's hard-line position is unpopular in Hong Kong and the pro-democracy camp is expected to dominate in September elections.

To ease concerns over the military parade, the PLA invited pro-democracy leaders to the event. The Democratic Party's chairman Yeung Sum accepted the offer and applauded the army's professionalism.

Mr. Yeung said he was sorry he could not speak to any of the military leaders. He said he hopes pro-democracy politicians will be able to visit Beijing following the September elections.

Many democracy advocates have been barred from traveling to the mainland over the past 15 years.

In Hong Kong, many people are deeply suspicious of the PLA because of its role in the bloody crackdown on the student-led pro-democracy demonstrators in Tiananmen Square in 1989.