Two powerful bombs have ripped through the main building of the Russian-backed Chechen Government in Grozny, killing at least 46 people in an apparent suicide attack.

Two vehicles, a truck and a jeep, smashed through security barriers around the building and exploded as employees were returning from lunch on Friday.

Dozens of people, including a deputy prime minister and the head of the Chechen Security Council, were wounded in the blast.

The death toll may continue to rise

President Vladimir Putin called the attack an "inhuman" act that "deeply stunned Russia".

"Those who prepared and performed this inhuman terrorist act are making war on their own people. But no amount of base crimes can break the Chechens' will and desire for a peaceful life," Mr Putin said in a telegram to the head of the Grozny administration, Akhmad Kadyrov.

Russian officials blamed the forces of Chechen rebel leader Aslan Maskhadov for the attack, but his top spokesman told Ekho Moskvy radio that his forces "do not follow such tactics".

The blasts, which occurred at about 1430 local time (1130 GMT), were the worst suicide bombing ever in Russia, the BBC's Steve Rosenberg says.

They demolished Moscow's claim that life is returning to normal after nearly a decade of war between the Russian military and Chechens fighting to make them leave the republic, he says.

If the bombing does prove to be the work of rebels, it would be their biggest operation since a group took hostage an audience at a Moscow theatre in October.

Nearly 130 hostages and all 41 Chechens died when Russian special forces stormed the building three days later.

The Kremlin stepped up its campaign against Chechen rebels after the theatre siege.

Big operation

The explosions ripped the facade off the government building and shattered windows kilometres away.

"There are many dead and injured, as it was a working day and many people were having lunch in the canteen," an official in Grozny said.

As night fell, rescue workers used heavy equipment to try to remove sections of the collapsed building in a search for survivors.

NTV reported that between 150 and 200 people normally work in the building, one of the few in Grozny to have been repaired after years of war.

The official Chechen armed forces do not follow such tactics Akhmad Zakayev, Maskhadov spokesman

The Kremlin spokesman said at least a metric ton of explosives was believed to be involved in the blast, which left a crater six metres (20 feet) deep.

Neither Mr Kadyrov nor his deputy Mikhail Babich were in the building.

Mr Kadyrov was in Moscow at the time but flew back to Grozny immediately.

In an interview with Russia's Interfax news agency, he appeared to admit that guerrilla forces operate freely in Grozny.

He said the security practice of stopping cars had proven "useless".

"Terrorists act as if they were masters of Grozny," he was quoted as saying.

Blame

Mr Kadyrov blamed the attack on Mr Maskhadov, who was elected president of Chechnya during a lull in hostilities in the mid-1990s and asserts that he still holds the post.

Terrorists act as if they were masters of Grozny Akhmad Kadyrov, Chechen administration head

His chief spokesman, Akhmad Zakayev said Mr Maskhadov's forces would not have carried out such an attack.

"If what's happened is the work of suicide bombers, then I can tell you with full authority that the official Chechen armed forces do not follow such tactics," he said, referring to Mr Maskhadov's claim to still be the legal president.

Some wounded were treated at the scene

Police stepped up security across the country in response to the bombing.

In Moscow, vehicle inspections were stepped up and identities were checked at railroad stations, airports and other public places.

President Putin, who came to power on the back of popularity gained by being tough on Chechnya, is pushing for a referendum on a proposal that would keep the republic within the Russian Federation.

A vote is planned for March.