The elections were triggered by the resignations in January of five pan-democrat lawmakers who hoped to offer voters the chance to show they wanted 'genuine' democracy.

But Beijing condemned the exercise, government-friendly parties declared a boycott and Chief Executive Donald Tsang Yam-kuen and his ministers said they would not vote.

Interim results early this morning showed the five - Tanya Chan and Alan Leong Kah-kit of the Civic Party, and Leung Kwok-hung, Wong Yuk-man and Albert Chan Wai-yip of the League of Social Democrats - were on course for comfortable victories.

On Thursday the league said it would consider the by-elections an 'unprecedented success' if turnout reached 25 per cent. Speaking after polls closed, Civic Party leader Audrey Eu Yuet-mee said the turnout was satisfactory.

'It is the biggest mobilisation since the July 1 demonstration in 2003, when 500,000 took to the streets. Each of the 500,000-plus votes counts and the government must respond to public demands for democracy.'

According to an exit poll by the University of Hong Kong, more than 50 per cent of 2,000 respondents said they had voted to fulfil their civic duties. Sixty-five per cent said they backed the 'de facto referendum', and 59 per cent said they opposed the government's reform proposals.

In the 2008 Legco election, the Civic Party and the league, together with their allies, received 881,184 votes in the five geographical constituencies, winning 19 seats.

Despite 24 contestants taking part yesterday, there was little election atmosphere, with the five former lawmakers the only visible campaigners. Many lesser-known candidates did not even put up a fight during the 15-hour polling period.

Tsang broke with his habit of going to Sunday Mass in the Wah Yan College, and made no public appearance all day.

Speaking after visiting a polling station, Stephen Lam Sui-lung, secretary for constitutional and mainland affairs who did not vote, said: 'The turnout rate is the lowest since the handover for Legco general elections and by-elections. It indicates a rather low level of support. Our judgment is that these by-elections could have been avoided, and the mainstream public opinion did not support this exercise.'

One of the few major public figures to back the by-elections was Catholic Cardinal Joseph Zen Ze-kiun, who said: 'Without a democratic system, there can be no improvement in people's livelihood. This referendum is an unusual chance for us to demonstrate our anger through peaceful means.'

Of the five constituencies, the highest turnout by 9.30pm was 19.51 per cent in Kowloon West, where Wong was challenged by Pamela Pak Wan-kam, a former agony aunt.

'No wonder we are getting this result because of the total boycott by government supporters and the pulling back of support by our pan-democrat allies,' Wong said.

Turnout was lowest in the New Territories West constituency - at only 13.41 per cent an hour before polls closed - where Albert Chan was trying to regain his seat.

Without credible challengers, both Leong and Leung had been running what some had seen as mundane campaigns in Kowloon East and the New Territories East.

An official said the by-election had distracted discussions of proposals for the 2012 elections. 'The low turnout rate may ease the pressure on moderate pan-democrats who are seeking dialogue with the government,' the official said.

But Democratic Party chairman Albert Ho Chun-yan said the results would not affect his party's resolve to veto the proposals if no major concessions were made.

Chinese University academic Ivan Choy Chi-keung attributed the low turnout to confusing messages put out by pan-democrats and the boycott by government allies. Tam Yiu-chung, leader of the Democratic Alliance for the Betterment and Progress of Hong Kong, said the by-election ploy 'was a failure'.