The UN nuclear watchdog earlier said the incident occurred at about 2:30 a.m. local time (00.30 GMT) on Sunday in a storage room at a nuclear laboratory in Seibersdorf, 35 kilometers (22 miles) south of Vienna. It also said however that no nuclear radiation had been detected outside the lab.
"Everything indicates that the radiation has not escaped into the environment," an IAEA spokesman said.
He said the lab was equipped with multiple safety systems to prevent the release of radioactivity into the environment and that no one was present in the lab at the time of the incident.
In November 2007, IAEA chief Mohamed El-Baradei asked the agency's member states to make $39.5 million available to modernize the lab, which was built in the 1970s and is considered outdated.
An IAEA spokesman said however that Sunday's incident was a one-off event and could have happened in even the most advanced laboratory.