Syria has agreed to a vist by inspectors from the Vienna-based International Atomic Energy Agency to a nuclear site for the first time since June 2008, diplomats said Wednesday.

The site, at Homs in the west of the country, is known to the IAEA and is not thought to be suspect.

"Syria has agreed to the principle of a visit," said a source close to the IAEA. It is due to take place on April 1 though the details remain to be determined.

The agreement follows numerous requests and growing impatience on the part of the agency with Damascus's refusals.

The visit will not take in a posible uranium enrichment facility at Al Kibar, which was bombed by Israeli warplanes in 2007, the source said.

News of the visit comes a week before the next meeting of the IAEA's board of governors, to be held from March 7 to 11, during which they will scrutinise Syria's case.

Satellite photos published by a Washington think tank last week appear to show Syrian efforts to conceal a second suspected nuclear site allegedly linked to the reactor bombed by Israel in 2007.

The photos acquired by the Institute for Science and International Security (ISIS) could lead the UN nuclear watchdog to step up demands for inspections.

The photos show heightened activity and the pouring of a concrete foundation around the site near Marj as Sultan, outside Damascus, shortly after a May 2008 request for inspections by the IAEA.

"The facility's operational status is unknown. However, there is suspicion that Syria may have emptied the buildings prior to mid-2008 and taken steps to disguise previous activities at the site," the ISIS report said.

"Laying down a new foundation could be an attempt to defeat the environmental sampling that IAEA inspectors would likely carry out to see if uranium was present in the event of a visit to these suspect sites," it said.