Two and a half tonnes of uranium have gone missing from a site in Libya, the UN's nuclear watchdog has said.

The International Atomic Energy Agency (IAEA) sounded the alarm after a visit by its inspectors to the undisclosed site earlier this week.

They found that 10 drums containing uranium ore had disappeared, the IAEA said.

There are fears the uranium could pose a radiological risk as well as nuclear security concerns.

In a statement, the IAEA said it would conduct further activities "to clarify the circumstances of the removal of the nuclear material and its current location".

It is unclear when the uranium went missing. Inspectors had reportedly wanted to visit the location last year, but the trip had to be postponed because of fighting between different Libyan militias.

The IAEA said that the site where the uranium was stored was not in government-controlled territory.

Since Libya's former dictator Colonel Muammar Gaddafi was deposed in 2011, the country has been divided into competing political and military factions.

It is now split between an interim government in the capital Tripoli and another one in the east.