Russian police say two people were killed when a small bomb exploded at an apartment block in St Petersburg last night. Initial reports had suggested a gas leak was responsible. The latest blast hit Russia's second city, St Petersburg, late yesterday, killing two people and injuring four. But police said they did not believe it was linked to the more powerful explosions over the past two weeks in Moscow and the southern towns of Volgodonsk and Buinaksk. Criminal underworld attacks are relatively common in Russia. Nobody has claimed responsibility for any of the blasts, but officials have blamed Chechen warlords fighting Russian rule in the North Caucasus region of Dagestan.

The Chechen leadership, which has little influence over the warlords, has denied involvement in the attacks. So has Shamil Basayev, head of the separatist fighters in Dagestan.

Russia's upper house of parliament applauded Prime Minister Vladimir Putin's security crackdown on Friday following a string of bomb blasts which have killed nearly 300 people and shocked the nation. But the generally loyal regional governors who make up the Federation Council sent a warning to President Boris Yeltsin by voting less than convincingly against deciding to debate a call for the embattled Kremlin chief to quit.

The bombs, and their political ramifications, also preoccupied investors with top Russian shares falling by as much as 11 percent, partly fuelled by rumours that Yeltsin was set to fire Putin. One of the myriad rumours floating around Moscow has Yeltsin appointing Lebed to replace Putin. Former paratroop general Alexander Lebed, now governor of Siberia's Krasnoyarsk region, said the bombs had stretched people's faith in the authorities to breaking point.

The Russian military, fresh from battling Islamic rebels in the southern region of Dagestan, is reported preparing a major military operation against its neighbour, the breakaway province of Chechnya. Officials would not comment on the reports, which revived memories of Russia's ill-fated 1994-96 military campaign to quell Chechnya's independence bid. Tens of thousands of people, mostly civilians, died during that conflict.