Tinsukia (Assam), Jan 8 (IANS) Two powerful explosions rocked India's violence-torn northeastern state of Assam Monday injuring five people, while separatists continued targeting Hindi-speaking migrant workers killing two more, taking the toll in four days of attacks to 68, an official said.

A police spokesman said five shoppers were injured in two simultaneous explosions around 7.20 p.m. Monday close to an army cantonment on the outskirts of Assam's main city of Guwahati.

"The blast took place near an evening vegetable market just adjacent to the main entrance to the army cantonment," a senior police official said. The injured were shifted to hospital with multiple injuries.

"The identities of the injured were not immediately known and we are investigating the incident," the official said.

In another attack, heavily armed militants gunned down two Hindi-speaking vegetable vendors and wounded five more at village Gelabeel in the eastern Golaghat district, about 320 km from Guwahati.

These two incidents are the latest in a series of attacks targeting Hindi-speaking migrant workers that began Friday night.

"The death toll has now mounted to 68, a majority of them Hindi-speaking migrant workers," Assam government spokesman and Health Minister Himanta Biswa Sarma told IANS.

Authorities have blamed all the attacks on the outlawed United Liberation Front of Asom (ULFA), a rebel group fighting for an independent homeland in Assam since 1979.

The ULFA is yet to take responsibility for the attacks.

Indian authorities Monday launched a massive anti-insurgency operation in the northeastern state of Arunachal Pradesh to hunt for ULFA rebels.

"Security forces of both Assam and Arunachal Pradesh have begun a joint offensive to flush out ULFA rebels believed to be taking shelter here," Arunachal Pradesh police chief Amod Kanth told IANS by telephone from the state capital Itanagar.

Five districts of Arunachal Pradesh share common border with Assam. Intelligence reports indicate that the ULFA was using at least three districts in the region as bases to carry out their hit-and-run guerrilla strikes in Assam.

The security operation is mainly confined to the extremely hostile and thickly wooded terrain in Tirap, Changlang and Lohit districts of Arunachal Pradesh, bordering eastern Assam.

"It is suspected that the ULFA could be using these areas as bases and hence the joint security operation," the police chief said. Intelligence officials said the ULFA guerrillas use Arunachal Pradesh as a transit route to their training bases in Myanmar.

It is not immediately known if the army was involved in the operation in Arunachal Pradesh.

Meanwhile, federal soldiers are combing pockets in eastern Assam following the recent wave of violence.

"Security forces are out in the field doing their job. Wherever is necessary, offensives are on," Assam Chief Minister Tarun Gogoi said.

Railway minister Lalu Prasad Yadav Monday appealed to the Hindi-speaking community for restraint and said New Delhi would do its best to ensure security to their lives.

"We shall do whatever is required to instil confidence among the Hindi-speaking people here," the minister said during a daylong visit to violence-torn eastern Assam.

He visited the injured and families of those dead in Tinsukia and Dibrugarh.

Most of the victims were from the eastern state of Bihar who had made Assam their home for decades and were doing odd jobs as brick klin workers, fishing, and as daily wage earners.

In 2000, ULFA militants killed at least 100 Hindi speaking people in Assam in a series of well-planned attacks after the rebel group vowed to free the state of all 'non-Assamese migrant workers'.