Syria has increased activity at a suspected chemical weapons production site, a move likely to increase tension with Israel, Jane's defence information group said Wednesday.

Satellite imagery of the Al Safir site in northwest Syria does not suggest that Damascus is arming for an offensive but will fuel concern in neighbouring Israel, the respected group said.

"The satellite imagery that ... Jane's has examined suggests that Damascus has sought to expand and develop Al Safir and its chemical weapons arsenal," said Christian Le Miere, editor of Jane's Intelligence Review.

"Further expansion of Al Safir is likely to antagonise Israel and highlight mutual mistrust, even as peace talks between the two neighbours progress intermittently," he added.

The London-based information group said it studied imagery from commercial satellites taken between 2005 and 2008.

"The site contains not only a number of the defining features of a chemical weapons facility but also that significant levels of construction have taken place at the facility's production plant and adjacent missile base.

"This does not suggest that Syria is arming itself for an offensive but it could have regional security implications given Syria's tension with its neighbour, Israel," it said in a statement.

A clear sign that it is a military facility, and not a civilian complex, is the level of security -- overall access is via a military checkpoint and there are more security points between different parts of the site, Jane's said.

Le Miere added: "Construction at the Al Safir facility appears to be the most significant chemical weapons production, storage and weaponisation site in Syria.

"Its presence indicates Syria's desire to develop unconventional weapons, either to act as a deterrent to conflict with Israel or as a force enhancer should any conflict ensue," he added.