Montreal's mayor is standing by the city's police chief amid new reports of police surveillance of journalists' phones.

Denis Coderre says asking Chief Philippe Pichet to resign without a full inquiry would amount to a "public lynching."

La Presse reported Saturday that police obtained a warrant to listen to two journalists' phone calls.

Pichet responded by saying the department only tapped the phones of its own officers who were under investigation for alleged crimes, although anyone they spoke to may have been overheard.

He had previously said surveillance of a columnist's iPhone was restricted to logging incoming and outgoing numbers and activating the phone's GPS chip.

Coderre says he has asked a legal expert to investigate the claims of surveillance on behalf of the city, but is not asking Pichet to step aside.

"(Journalists) must protect their sources and that's part of democracy and I support that, but we also live in a society of laws" Coderre told a news conference on Sunday.

"Living in a society of laws means we won't start lynching people in public and we won't condemn someone until we have all the facts."

The Quebec government has announced an inquiry will be held into the monitoring after Montreal and Quebec provincial police admitted that several journalists were put under surveillance and had their cellphone logs tapped.