Pro-democracy lawmakers on Tuesday appealed to their pro-government rivals to back a move to summon top officials to Legco over the decision to stop Financial Times journalist Victor Mallet from working in Hong Kong.

The pan-dems said the refusal to renew Mallet's visa has tarnished Hong Kong's international reputation and they want answers from Chief Executive Carrie Lam, Security Secretary John Lee and Immigration Director Erick Tsang.

The main theory being bandied about is that the move is in response to the editor overseeing a talk at the Foreign Correspondent's Club in August by pro-independence activist Chan Ho-tin.

But the authorities have so far refused to confirm or deny this, despite demands for an explanation from among others the Financial Times, the British government, and lawyers and journalist groups in the SAR.

A motion to require the officials to testify before Legco is expected to be debated on October 24, but will fail unless the pro-democracy camp can secure the backing of pro-establishment legislators.

Opposition lawmaker Claudia Mo said the SAR government clearly believes it has been wronged by Mallet and is trying to teach him a lesson. She said it is therefore important that Legco gets to the bottom of the saga.

"This particular case involving Mr Mallet is quite unusual. It's so blatant and vicious on the part of the Hong Kong government to try to victimise one particular person, one foreign journalist," Mo said.