Four bomb blasts killed eight people in Assam on Monday, a day before Prime Minister Manmohan Singh was due to visit the region, police said.

Police said the state’s main separatist group, the United Liberation Front of Asom (ULFA), was behind the attacks.

Singh’s visit to the state would go ahead as scheduled amid tight security, a spokesman for the ruling Congress party said.

The first bomb exploded in a crowded parking area in front of a restaurant in Guwahati, killing seven on the 30th anniversary of the founding of ULFA, police said.

“Seven people have died in the blast,” P.C. Saloi, a senior police officer in the city, told Reuters by phone.

At least 32 people were injured and several of them are in a critical condition. The death toll is likely to rise further, officials said. Several vehicles and buildings caught fire after the blast.

A second bomb went off two hours later opposite a hospital in the town of Dhekiajuli, 150 km north of Guwahati. Police said the device was planted on a bicycle. Six people were injured, three of them critically.

The third blast occurred at Jengpha, in Assam’s Karbi Anglong district, but no one was injured.

Rebels also threw grenades at a police station at Mankachar town in Dhubri district, near the border with neighbouring Bangladesh, killing one and wounding five people.

Accusing the police of not providing adequate security, hundreds of angry protesters blocked Guwahati’s main street, shouting slogans and clashing with the police.

Political parties have started campaigning in the state ahead of an April-May general election.

Last week a bomb blast killed one person in Guwahati, close to where Foreign Minister Pranab Mukherjee had been due to address an election rally. The rally was subsequently cancelled.

The ULFA is among more than two dozen armed groups in India’s northeast which are either fighting for an independent homeland or more political autonomy.

They accuse New Delhi of plundering the region’s mineral and forest resources, neglecting the local economy and giving them back nothing in return.