The explosions occurred within a minute of each other

Two bombs exploded in the main commercial centre of Dimapur town in Nagaland - one at a train station and another at a local market.

At least 28 people were killed and more than 100 injured in the morning blasts.

Hours later, rebels from the Bodo tribe sprayed shoppers with bullets in the neighbouring state of Assam, killing at least 20 people, police said.

They suspect the rebels - the National Democratic Front of Bodoland (NDFB) - may have been behind the Nagaland attacks too.

There are many separatist rebel groups in north-east India.

Carnage

The largest explosion occurred at the Dimapur railway station, which was crowded with passengers at the time. The other bomb went off in the local Hong Kong market within a minute.

Local trader Alok Pareek said limbs and severed heads were strewn about the railway station and the market, which is openly used to sell contraband goods.

He said the entire structure in front of the station master's office had collapsed.

"Many who died were trapped in the debris in the railway station," he said.

Doctors have warned that the death toll could rise.

BBC correspondent Subir Bhaumik says eyewitnesses report that passengers who were waiting for trains at the station were flung on the tracks by the force of the explosion.

He adds that many of them had been delayed in Dimapur for several days because of a strike in the neighbouring Karbi Anglong district of Assam, which connects Nagaland to the rest of the country.

An indefinite curfew has been ordered in Dimapur.

There has been an insurgency in Nagaland since 1956, but for the last seven years the state's major separatist group, the National Socialist Council of Nagaland (NSCN), has been negotiating with the Indian government, and its fighters are observing a ceasefire with the government's security forces.

Both factions of the NSCN have condemned the explosions.

Indiscriminate firing

Another explosion on Saturday, in the Santipur market of Kokrajhar district, in the neighbouring state of Assam, killed one trader and injured seven others.

This was followed by about six other attacks in which Bodo rebels fired indiscriminately at shoppers at three village markets in Makri Jhora village, 20km (16 miles) west of Assam's main city of Guwahati.

At least 19 traders and parents belonging to non-Bodo communities were killed. More than 20 people were injured in the attacks.

The NDFB has suffered a lot of casualties during Indian and Bhutanese military operations in the last year and the intelligence officials say they were perhaps striking back now.