MOSCOW (Reuters) - Russian President Vladimir Putin, his trip to Asia canceled over weekend suicide bombings, issued a fresh vow on Monday to crush Chechen separatists by rooting them \"out of cellars and caves.\" Moscow city authorities declared Tuesday a day of mourning for the 13 rock concert-goers who died when two women wired with explosives blew themselves up. News reports said five people remained in hospital in serious condition. New violence was reported from Chechnya itself. Military sources said a helicopter which crashed on Sunday, killing five servicemen, may have been shot down. Putin chaired his weekly meeting with senior ministers after canceling a trip to Uzbekistan and Malaysia. He said only uprooting terrorism would solve Russia\'s problems. \"The bandits acting in Chechnya are part of the international terrorist network,\" a grim-looking Putin was shown telling the Kremlin meeting on national television. \"With such people it is pointless carrying out preventive measures. They must be rooted out of the cellars and caves in which they are hiding and destroyed.\" No state, he said, would be \"pushed around by terrorists. Nor will Russia. The first step in such a direction will mark the beginning of the collapse of the state and the number of victims will rise dozens, hundreds, thousands of times.\" Security forces link Saturday\'s attacks to Chechen rebels who have been fighting Russian rule in the southern region for a decade, though no one has yet claimed responsibility. The bombing brought mass violence back to the city of more than 10 million for the first time since separatists, including women with explosives strapped to their waists, held hundreds of theater-goers hostage for three days last October. A total of 129 hostages died when security forces used gas to rescue them. (Reuters)