A blast occurred at a garden centre in Moscow on Thursday, possibly during welding work, state news agency RIA reported.
A spokesman for Moscow city police said the force was not immediately available to confirm if an explosion had taken place. RIA said it was unclear if there were any casualties.
Interfax news agency said a blast had been reported in the car park of the garden centre on Moscow's main circular road.
The Kremlin is fighting an Islamist insurgency in its mainly Muslim North Caucasus region along its south, and in recent years rebels have taken their fight to the Russian heartland.
Russia's top security official, Alexander Bortnikov, told President Dmitry Medvedev earlier this week that a large-scale militant attack in or around the capital had been foiled -- a rare admission for authorities to make.
Bortnikov, who heads the Federal Security Service, successor to the Soviet-era KGB, said militants armed with homemade bombs and other weapons were planning to attack Moscow.
ReutersGüncelleme Tarihi: 21 Temmuz 2011, 17:23