The International Atomic Energy Agency says plutonium has leaked in one of its laboratories but no radiation escaped the building.

The IAEA added that no one was hurt in the Sunday incident. The leak took place in the high security area of its nuclear lab in Seibersdorf, 35 Km (20 miles) south of Vienna, AP reported.

"Pressure buildup in a small sealed sample bottle in storage safe resulted in plutonium contamination of a storage room," the agency said.

It went on to add that the incident took place at 00:30GMT on Sunday while no one was in the lab. The IAEA rejected the possibility that the incident was an act of sabotage, according to one of its spokesmen, Ayhan Evrensel.

Meanwhile, Daniel Kapp, a spokesman for the Austrian Environment Minister Josef Proell, said that no nuclear radiation was measured outside the lab.

The IAEA is the UN's nuclear watchdog, and the lab routinely analyzes small samples of nuclear material like uranium or plutonium as part of the agency's safeguards certification.

In November 2007, IAEA Chief Mohamed ElBaradei asked the agency's member states to make USD 39.5 million available in order to modernize the lab since it was built back in the 1970s and the agency believed it was outdated.

However, IAEA spokesman Evrensel said that Sunday's incident was a one-time event that had nothing to do with the lab being outdated.

Austrian officials said the empty lab was sealed off and no-one was at risk. A full investigation has been planned to find the cause of the incident.

SM/MMN