A subisidiary of French IT firm Bull helped Moamer Gaddafi's regime spy on the emails and chat messages of opponents of the fallen Libyan strongman, a report said Tuesday.

Amesys, which on its website describes itself as "a key player in the field of security and critical systems at national and international levels," installed a monitoring centre in Tripoli in 2009, the Wall Street Journal said.

The paper, quoting people familiar with the matter, said the firm equipped the centre with "deep packet inspection" technology to snoop on the online activities of Gaddafi's enemies.

The Libyan regime earlier this year held talks with Amesys and other firms, including Boeing's Narus unit, a maker of internet traffic-monitoring products, as they sought to boost the regime's surveillance apparatus, the Journal said.

Chinese telecom firm ZTE also provided technology for the monitoring operation, the report said.

Bull said it had no comment to make on the report when contacted by AFP.

Narus told the Wall Street journal: "There have been no sales or deployments of Narus technology in Libya," while ZTE declined to comment when approached by the daily.

The Journal said that its journalists had toured the surveillance centre and found files there that include emails written as recently as February, after the Libyan uprising kicked off.