In an Internet posting, a Chechen rebel leader with a $10 million bounty on his head has apparently asserted responsibility for the Beslan school siege and threatened more attacks on Russian civilians if Chechnya is not granted independence.

The defiant, taunting and rambling missive, allegedly written by Shamil Basayev, whom Russian authorities have blamed for the massacre, offered the guerrilla's version of events in southern Russia early this month in which 338 people, many of them children, were killed. It expressed some passing regret at the loss of life, which the posting blamed on President Vladimir Putin.

"The Kremlin vampire destroyed and wounded 1,000 children and adults by giving the order to storm the school for the sake of imperial ambitions," the message stated. It bore the signature Abdallakh Shamil, an alias previously used by Basayev.

"We are sorry about what happened in Beslan," the message said. "It's simply that the war, which Putin declared on us five years ago, which has destroyed more than 40,000 Chechen children and crippled more than 5,000 of them, has gone back to where it started."

The message also asserted responsibility for the downing of two Russian airliners and a bombing outside a Moscow subway station in late August. In all, the recent attacks have killed more than 400 people.

The statement was posted Friday on a separatist-oriented Web site called Kavkaz-Center, based in Lithuania. After a meeting of the Lithuanian government, Prime Minister Algirdas Brazauskas said the site would be closed.

Russian officials said the posting was no surprise. "Basayev once again demonstrated his true face, the face of a terrorist and murderer who will stop at nothing, even mass death for schoolchildren," Maj. Gen. Ilya Shabalkin, spokesman for Russian forces in the North Caucasus region, told the Russian news agency Interfax.

Basayev, 39, was one of the republic's most feared guerrillas during the first Chechen war in the mid-1990s. After Russian forces withdrew from the republic at the end of that conflict in 1996, he became deputy prime minister in a Chechen government.

War resumed in 1999, and he is alleged to have organized some of the most notorious attacks of recent years, including the 2002 siege of a theater in Moscow.

After the Beslan siege, Russia offered a $10 million reward for Basayev's capture or killing and put a $10 million bounty on Aslan Maskhadov, the former Chechen president, who condemned the seizure of the school in Beslan.

At an international conference of mayors in Moscow on Friday, Putin reaffirmed his refusal to negotiate with the Chechens and said "we in Russia are engaged in serious preparations at the moment to act against terrorists in a preventive manner."

The Basayev message said the massacre at the school began because Islamic fighters inside "made a fatal mistake" by allowing a Russian emergency services vehicle onto school grounds to remove bodies of people killed on Sept. 1, the first day of the siege.

Russian troops used the pickup as cover to enter the school grounds, the message asserted. Two hostage-takers who had come outside to observe the removal of the bodies were killed by the troops, who triggered an explosion inside the school and began a full-scale assault, according to the posting.

The message said the guerrillas had deployed 20 mines inside the school, connected in one electronic circuit. "I personally trained this group in a forest, and I tested this system," the message said. "Either all bombs would have exploded or not a single one," but none detonated, the message said.

Suggesting that the victims were killed by Russian bombs, the message said: "We suggest that independent experts should check the fragments and types of wounds."

Numerous survivors of the siege have said that the first explosion occurred inside the gym and was caused by one of the guerrillas' devices. Russian officials said that blast triggered a firefight and bloody inferno as hostages fled the building and unprepared troops were forced to attack. By official count, 338 people were killed.

The message asserted that the hostages would have been freed if the Russians had withdrawn from Chechnya or if Putin had resigned.

The message said there were 33 hostage takers, mostly Chechens and Ingush, but also two Arabs, confirming Russian statements that Arabs were present, but not the 10 they originally asserted.

The message continued: "I don't know Bin Laden, don't receive any money from him, but would not mind." The message said little financing comes from abroad. The school siege cost about 8,000 euros (about $9,800) to mount, it said, adding that the weaponry used had been stolen from Russian forces or, as the message put it, "deducted from the Russian budget."

Shamil Basayev had been accused by Russia of directing the Beslan school seizure.