Saboteurs blew up Yemen's main oil export pipeline on Wednesday, interrupting flows of crude oil to a major export hub, the country's defense ministry said.

It was the latest assault on the country's main source of income, as Yemen relies on oil and gas exports for 90 percent of its foreign currency earnings.

The motive for the latest attack was not immediately clear, but previous acts of sabotage by tribesmen have targeted oil and other infrastructure in a bid to extract concessions from the central government.

The defense ministry said on its website, www.26sept.net, that the attack occurred in the area of Habab in Marib province.

Some 70,000 barrels are pumped through the Marib pipeline a day to Ras Isa, a crucial petroleum export terminal on the Red Sea.

According to government figures, attacks on infrastructure have cost the impoverished nation $4.5 billion (3.6 billion euros) between March 2011 and March 2013 alone.

hg/cjc (Reuters, AFP, dpa)