At least 68 people have been killed in a string of explosions today in India's northeastern state of Assam.

Assam state Chief Minister Tarun Gogoi told a news conference: 'The death toll so far is 61 and 300 injured, with more than 75 of them critically injured.'

Mr Gogoi said six blasts occurred in Assam's largest city, Guwahati, while three bombs went off in the district of Kokrajhar, two in the town of Barpeta and the 12th explosion occurred in Bongaigaon city.

No one has claimed responsibility for the bomb blasts. Assam has been a focus of a separatist insurgency for decades, but it has also recently suffered bomb attacks blamed on militants from neighbouring Bangladesh.

Firefighters doused the smouldering remains of cars and motorcycles in Guwahati. One of the blasts targeted a high-security zone with a court as well as offices and the homes of senior police officials.

Many of the blasts were in crowded markets.

Television channels showed some people lying on the streets, their clothes soaked in blood. Some of the walking wounded were helped into ambulances by local people and police.

A wave of bomb attacks has hit India in recent months, killing more than 125 people.

Last month, Assam state was also hit by clashes between indigenous tribes and Muslim settlers that killed at least 47 people.

Pakistan PM condemns attacks

Senior police officer GP Singh said two of the bombs in Guwahati were hidden in motorcycles or scooters.

Pakistan, often blamed by New Delhi for fomenting trouble in neighbouring India, condemned the attack and called for international cooperation to tackle strikes by militants.

'Prime Minister Yousaf Raza Gilani has strongly condemned the bomb blasts,' an official statement said. 'He deplored the loss of lives. Pakistan condemns terrorism in all its forms.'

Pankaj Goswami, a witness at a blast in Guwahati, said: 'The impact of the blast was so huge, a packed bus got half burnt and we pulled out a lot of injured people and sent them to hospital.'

Local television said a curfew was imposed in Guwahati after angry crowds attacked police and set cars on fire. Police fired in the air to disperse the angry mob.

'Immediately after the blast there was complete darkness for a while and I later saw several bodies and severed limbs all around,' said Bikash Goyal, a witness in Guwahati.

In October, at least two people were killed and 100 injured in four bomb blasts in Assam that police blamed on militant groups based in neighbouring Bangladesh.

But the separatist United Liberation Front of Asom, fighting for an independent homeland for the state's more than 26m people, is often suspected of being behind attacks.

Ringed by China, Myanmar, Bangladesh and Bhutan, India's northeast is home to more than 200 tribes and has been racked by separatist revolts since India gained independence from Britain in 1947.

Local citizens accuse New Delhi of taking away the region's mineral and forest resources, neglecting development and allowing in a flood of outsiders.