ST PETERSBURG (REUTERS) - Russia said on Wednesday 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 that 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 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".