The north was seen as one of Chechnya's safer areas
The number of people known to have died as a result of Monday's truck bomb in Chechnya has risen to 54, while more than 80 remain in hospital.
Russian President Vladimir Putin linked the style and consequences of the bombing to suicide attacks in Saudi Arabia on Tuesday which left at least 29 people dead.
The Chechnya attack destroyed a local government compound in Znamenskoye, in the north of the republic, and damaged neighbouring residential buildings.
Prosecutors say people suspected of organising the attack, which was carried out by suicide bombers, are being pursued.
Among the dead were seven children and 10 officers of the Federal Security Service (FSB), whose local branch was located in the compound.
The attack - blamed by Moscow on Chechen separatists - was the deadliest attack since a December suicide bombing in Grozny.
Mr Putin suggested that there could be links with the attacks in the Saudi capital Riyadh, which have been blamed on al-Qaeda.
Major rebel attacks
Dec 2002 - Suicide attack on Grozny government kills 80
Oct 2002 - Rebels seize Moscow theatre - 120 die in rescue bid
Aug 2002 - Giant Russian military helicopter shot down, with at least 118 personnel killed
Mr Putin suggested that there could be links with the attacks in the Saudi capital Riyadh, which have been blamed on the al-Qaeda terror network.
Speaking during a meeting with the Nato Secretary-General, George Robertson, he said: "The imprint in this and that case is absolutely identical.
"The consequences are absolutely comparable."
However, the Russian daily newspaper Izvestiya, has suggested that the bombers may have targeted the offices for economic as much as political reasons.
It reported on Tuesday that the FSB had been taking a tough line against smugglers of oil and metal from Chechnya, who habitually pass through the surrounding Nadterechny region.
While some officials blamed the attack on the same group of rebels who carried out the December bombing, Russia's deputy prosecutor general said the groups were different but linked.
The blast left a crater at least 15 metres (yards) wide and four deep, gutting buildings at the scene and causing other serious damage within a radius of up to 500 metres.
Rescue workers pulled out 23 survivors from the ruins on Monday, and continued sifting through the rubble overnight.
Of those in hospital, 57 are described as being in a critical condition.
Twenty-three families were made homeless by the blast.
The head of Chechnya's pro-Moscow administration, Akhmad Kadyrov, said there were several questions that needed to be answered:
- Where did the lorry come from?
How did it avoid military checkpoints, and get so close to administrative buildings?
How was the attack possible in one of the calmest parts of the republic?
He suggested that responsibility for fighting rebels should be should be switched to Chechnya's interior ministry instead of the FSB and federal troops.
Local government chief Sultan Ahmetkhanov said soldiers at the gates had opened fire on the lorry in an attempt to stop it, but the vehicle tore through the barriers.
Many local civilians would have been visiting the administrative offices on Monday as it was the first working day after Russia's May holiday period.