Four people have been killed in a bomb blast in Balochistan, even as heavy fighting erupted in the restive province where para-military troops conducted operations against rebels opposed to the construction of army contonments.

Four persons were killed and one tribesman injured in a bomb explosion in the Mashkal area of Kharan district, officials in provincial capital Quetta told Dawn daily.

The exchange of rocket fire occured on Sunday between security forces and Baloch nationalists who are opposed to construction of army cantonments and are demanding more autonomy for the province.

The Baloch nationalist Jamhoori Watan Party secretary general Agha Shahid Hasan Bugti accused security forces of attacking tribesmen without any provocation in Sungsila Corner, about four km from Dera Bugti road in South-West Balochistan in Sunday. He claimed that the tribesmen only returned fire.

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But district coordination officer Dera Bugti Abdul Samad Lasi blamed the tribesmen for launching an attack on two checkpoints on the Dera Bugti-Sui Road and ambushing the Loti gas-field vehicles in the Bashpage area which brought items of daily use for the employees.

Shahid said the two sides fired rockets at each other's positions in the Bekar area, adding there was no casualty on tribesmen's side. Two ambulances and troops reinforcement were seen rushing toward Dera Bugti.

Elsewhere in the province, six blasts rocked the Spin-Tangai area lying between Sibi and Harnai. One blast is believed to have damaged a portion of the railway track, the newspaper reported.

Another device went off near a gas pipeline in Kalat but did not cause much damage.