BOGOTA, April 5 (Reuters) - Colombian state oil company Ecopetrol (ECO.CN) has restarted the country's second-largest oil pipeline, the Cano-Limon Covenas, after a series of bomb attacks halted movement of crude for seven weeks.

The pipeline began pumping again during the night, army sources said on Wednesday. Pumping had stopped on Feb. 15 in one of the longest halts since the pipeline came online in 1986.

Ecopetrol said in March that rebel attacks on the pipeline had cost Colombia 893,000 barrels of oil production this year, more than a day's worth of total national output.

Military sources attributed the estimated 30 attacks so far in 2017 to the leftist National Liberation Army, or ELN, rebels.

The reopening of the pipeline should soon permit production to resume at the Cano Limon and Caricare fields in northern Colombia. U.S.-based Occidental Petroleum Corp (OXY.N) , which operates the fields, suspended output there in early March because of the attacks.

The ELN has about 2,000 combatants and opposes the presence of multinational companies in the mining and oil sector, saying they seize natural resources without leaving benefits to the country's population or economy.

According to Ecopetrol, attacks against the Cano-Limon pipeline have left 751 victims over the last 17 years, 167 of whom were killed. Since it opened, the pipeline has been out of service about 10.4 years, or 30 percent of its life. Some 66 million gallons of crude have been spilled since 2000.

The 485-mile (780 km) pipeline transports crude from the fields in Arauca province, near the border with Venezuela, to a port in the Caribbean Sea for export. The fields produce about 52,000 barrels per day, and the pipeline can carry up to 210,000 bpd.

Attacks on oil infrastructure by the ELN, which the United States and European Union consider a terrorist group, have been frequent during the group's five-decade war with the government. The attacks, which numbered 43 last year, cause oil spills and environmental damage.

President Juan Manuel Santos and the ELN began formal peace negotiations in Ecuador in February, but the group has stepped up its attacks since.

The ELN said in a video statement last week that it would continue attacks until companies listen to the rebels' environmental and social proposals.