Pakistani authorities say tribesmen have attacked a state-run natural gas facility in Baluchistan Province, setting fire to a portion of the national pipeline network in the southern part of the country.

Police say there were casualties during an extensive battle overnight between tribesmen and Pakistani paramilitary forces, but the number of those killed or wounded is not clear.

Reports also conflict on whether the pipeline attack interrupted natural-gas deliveries to southern Sindh province. Hours after the battle ended early today Saturday, officials said the pipeline was operating normally.

Authorities say fighting began during the night when tribesmen fired an intense volley of rockets at a Pakistan Petroleum Ltd. facility in Sui, about 300 kilometers southeast of the Baluchistan provincial capital, Quetta. Paramilitary forces guarding the installation responded with rockets and mortars, and the battle raged for hours.

Security at oil and gas installations in southwestern Pakistan has long been a cause of concern. Tribesmen in the area have been fighting for more autonomy and a share of the benefits from oil and gas exploration.