The nearly 2,700-mile Keystone oil pipeline was shut down Tuesday morning after it ruptured in North Dakota, halting the flow of millions of gallons of crude oil from Canada to refineries in the U.S.

The cause of the rupture and the total volume of oil released after the North Dakota spill remain unclear, officials said.

Malaysia's gas pipeline network plays a critical role in national industrialisation and energy efficiency, says corrosion specialist Kang Kim Ang.