FACTBOX: Iraqi oil facilities in and around Basra

(Reuters) - Heavy fighting continued on Thursday in the southern Iraqi city of Basra, the main hub for the country's vital oil production and exports.

One of two main crude export pipelines in the region was blown up on Thursday, a Southern Oil Company official said .

Iraq's government relies heavily on oil exports for revenue, and has sustained the flow from Basra even as a violent insurgency targeted the country's oil installations elsewhere.

Basra exports were last interrupted by pipeline blasts in 2004. Following are details on oil facilities in and around Basra.

- Iraqi oil output in the southeast is around 1.8-2.0 million bpd, according to Iraqi oil officials. That accounts for about 80 percent of Iraq's total output of 2.3 million bpd.

- The North and South Rumaila fields near Basra are Iraq's largest measured by output. South Rumaila produces around 800,000 bpd and North Rumaila about 500,000 bpd. A dozen smaller fields, including Suba, Luhais, West Qurna and Zubair, account for most of the rest of the region's output.

- Iraq's Southern Oil Company (SOC) operates the fields and has its headquarters in Basra.

- Basra oil terminal has the capacity to export around 82,000 barrels per hour, or nearly 2 million bpd. Exports in February were around 1.54 million bpd. Iraq also exports smaller amounts of crude from the Gulf port of Khor al-Amaya.

- The Shuaiba refinery in Basra province is Iraq's second largest with capacity of around 160,000 barrels per day. Shuaiba is currently producing around 100,000 to 110,000 bpd of oil products, according to a refinery engineer. The plant was hit by a fire in January, which the SOC blamed on a mortar attack.