The United States said on Tuesday that it was "very concerned" about the bombings in Moscow that killed at least eight people and injured 31 others after a car exploded outside a Moscow subway station.

"We have seen the reports of bombings in Moscow just recently. Obviously we are very concerned about the situation," State Department spokesman Richard Boucher said at a news briefing.

"We have always been willing to help the Russians or consult with them in these matters, and that offer remains open. But at this point, the Russians are investigating," Boucher said.

Citing a source in the Russian Federal Security Service (FSB), the Interfax news agency reported Tuesday that the car bombing near a subway station in northeast Moscow on Tuesday night was carried out by a female suicide bomber.

A car parked near the Rizhskaya subway station was blown up at about 8:15 p.m. Moscow time (1615 GMT) and caused heavy casualties,a medical source at the scene of the blast said.

The explosion came after Sunday's presidential election in Russia's Chechen republic, in which Kremlin-backed Alu Alkhanov won a landslide victory to replace pro-Moscow Akhmad Kadyrov who was killed in a terrorist bomb blast on May 9.

Precisely a week ago, two Russian passenger planes crashed almost simultaneously, killing all the 90 people aboard and raising suspect that terrorist attacks were behind the tragedies.

Source: Xinhua