Hong Kong chief executive hopeful Carrie Lam came under relentless attack by her two rival candidates in a televised debate held ahead of the March 26 election.

In the testy debate in Cantonese last night, former financial secretary John Tsang said Mrs Lam shared similarities with unpopular incumbent leader Leung Chun Ying, which earned her the nickname CY2.0.

The third candidate, retired judge Woo Kwok Hing, took aim at her HK$3.5 billion (S$637 million) Palace Museum project, which is the city's own version of the capital's famed Palace Museum.

He blasted the city's former chief secretary for abuse of power and a lack of transparency in going ahead with the project without first consulting the public.

Mrs Lam, 59, the front runner and seen as Beijing's preferred candidate in the leadership race, was put on the defensive as the two men took her to task for her past performances and poked holes in her manifesto.

Mr Woo, 70, accused her of engaging different consultancy firms to conduct fake consultations. She denied this and demanded that Mr Woo produce evidence to back up his allegation.

Mr Tsang, 65, who was previously on a committee to tackle the city's housing shortage issue, said Mrs Lam's proposal for building flats for Hong Kongers who are first-time buyers "will not work" because it is "impossible to find land" for it. He also alleged that her efforts in past years had been "fruitless". "You would start something, but there wouldn't be any results," he said.

"The Hong Kong Palace Museum is supposed to be a good thing, but the way you handled it, you have turned it in to a bad thing."

In the two-hour debate, organised by various media outlet at TVB City, the three candidates shared the same stage for the first time to spar on political, economic and livelihood issues, with the hope of winning over public opinion.

But to many Hong Kongers, the election on March 26 is not a "real" one as only 1,194 members of an elite Election Committee are tasked to pick the city's next leader.

Besides taking questions from media representatives and audiences, the three candidates also had the opportunity to engage in a "free fight" to attack one another.

Mr Woo appeared to be the most well prepared, according to political analyst Johnny Lau, who said the former judge produced a lot of statistics when talking about different issues. Mr Lau said the debate was a good opportunity for the two men to attack their less popular rival.

Civic Party chairman Alan Leong felt Mrs Lam committed a major error when she said she would resign if her views were not accepted by the mainstream. This allowed Mr Tsang to ask if she would quit the campaign since polls showed that she is unpopular, Mr Leong added.

To political analyst Willy Lam, it does not quite matter who performed the best last night because the people do not get to vote.