He cited anti-graft laws as an example, and said that under existing laws it might be illegal for political parties to ask members to stand for, or withdraw from, elections.

'You can say it is wrong if political parties exclude someone from their list of candidates or persuade someone to run by promising to share their election expenses,' Mr Ma said.

Political parties should be exempt from declaring expenses for legal advice given by party colleagues during elections, he said.

'[Democratic Party chairman and barrister] Martin Lee Chu-ming must have given advice to his colleagues. But how can you define whether he is giving legal advice or just talking to his friends?' Mr Ma said.

A comprehensive law regulating political parties was suggested to fit in with the development of party politics.

But a Constitutional Affairs Bureau spokesman said candidates from parties should not have privileges over other hopefuls.