'The city is getting more politicised. Out of 100 tasks, an official may have performed 99 of them excellently, and one of them slightly badly. But that single incident is usually picked out and criticised heavily,' Tang said.

'I've had this experience myself - you probably remember the HarbourFest incident.'

Tang said he had learned a lesson from the saga: 'When you think something is the right thing to do and you can hold yourself and others accountable, then you should do it.'

At the time, Tang was the secretary for commerce, industry and technology. He was accused of failing to take responsibility for the fiasco, in which oversight of the concert budget was thought to have been mishandled.

Tang arrived late at the forum and left early, but denied he was trying to avoid fellow candidate Leung Chun-ying. 'I had other commitments before and after the forum,' he said.

New People's Party chairwoman Regina Ip Lau Suk-yee, who says she is considering whether to enter the race for the top job, also spoke at the forum, which was organised by the National School of Administration's Hong Kong Alumni Association.

Leung invited civil servants to take part in drafting his manifestos.

The former Executive Council convenor defended criticism of his lack of experience working with civil servants, saying he had been involved in civil service issues in his three decades of public service.

Ip, a former senior official, said the next government needed to shoulder political responsibilities to reduce criticism from civil servants.