Russia said yesterday that a military strike on Syria could have catastrophic effects if a missile hit a small reactor near Damascus that contains radioactive uranium.

The Foreign Ministry called on the UN nuclear agency to urgently assess the risk as the United States considers military action to punish Syria’s government for an alleged gas attack.

“If a warhead, by design or by chance, were to hit the Miniature Neutron Source Reactor (MNSR) near Damascus, the consequences could be catastrophic,” a ministry statement said.

It said nearby areas could be contaminated by highly enriched uranium and that it would be impossible to account for the nuclear material after such a strike, suggesting it could fall into the hands of people who might use it as a weapon.

Russia urged the UN International Atomic Energy Agency secretariat to “react swiftly” and present IAEA members “an analysis of the risks linked to possible American strikes on the MNSR and other facilities in Syria”.

Moscow has been the most powerful ally of Syrian President Bashar al-Assad, shielding him from tougher UN resolutions and warning a Western attack on Syria would raise tensions and undermine efforts to end the civil war.

The Vienna-based UN agency had no immediate comment on the Russian statement.

The IAEA said in a report to member states last week that Syria had declared there was a “small amount of nuclear material” at the MNSR. Nuclear expert Mark Hibbs, of the Carnegie Endowment think-tank, said the MNSR was a very small reactor and there would not be a lot of material there.

But he said there could be “a serious local radiation hazard” if there was irradiated nuclear material in the reactor and it was dispersed by a weapon strike.

In 2007, Israel bombed a desert site in Syria that US intelligence said was a nascent, North Korean-designed reactor.