HONG KONG — Hong Kong residents began voting early Sunday in a legislative election that could give pro-democracy figures more clout than they have held since China reclaimed the territory from Britain in July 1997.

Polls opened under grey skies, with analysts predicting the opposition would gain the most popular support, while still falling short of a majority under rules critics say are badly rigged in favour of pro-Beijing parties.

Voters are directly picking 30 of the territory's 60 legislators. The other half are chosen by a relatively small group of special interest voters, such as business leaders, doctors and accountants, who tend to back pro-Beijing candidates.

Pro-Beijing politicians were campaigning hard Saturday on Hong Kong Island, hoping to knock out the territory's best-known opposition figure, Democratic Party legislator Martin Lee, in what polls showed to be one of the tightest races.

The chairman of the pro-Beijing Democratic Alliance for the Betterment of Hong Kong, Ma Lik, was stumping for votes after returning just two days earlier from mainland China, where he has received treatment for colon cancer.

"It's a very tight race," Lee acknowledged. "I'm doing my best to go for it."

Lee brought in help from a popular former radio host, Albert Cheng, who is expected to win a seat of his own in another district. Cheng is one of three radio hosts who went off the air in May, allegedly after receiving threats over their pro-democracy stances in one of the biggest controversies surrounding the political season.

Hong Kong election officials have promised that Sunday's polling will be free and fair, amid swirling allegations that some voters have been told to back pro-Beijing candidates and prove it by photographing their completed ballots with cellphone cameras. Such devices would be banned from the polling stations, officials said.

The mass-circulation tabloid Apple Daily urged the public to turn out and back pro-democracy candidates.