(Adds witness account of oil spill)

By Alonso Soto

QUITO, Feb 25 (Reuters) - Ecuador's second largest oil pipeline halted pumping Wednesday morning after the line was ruptured, but it had enough stock to cover February export commitments, the line administrator said.

Pedro Lopez, spokesman for the firm that administers the private, 130,000-barrel-per-day OCP pipeline, said the damage was being evaluated to determine when the line could restart operations.

The pipeline carries mostly heavy crude to the Pacific coast from private oil companies operating in the OPEC nation and an affiliate of state oil company Petroecuador.

"We are still evaluating the conditions of the pipeline ... We have no estimates to when the line can restart pumping," said Lopez, adding that the oil spill was contained.

Douglas Beltman, an environmental scientist on the scene, said a a tick layer of crude was covering a nearby river in the Amazonia province of Napo, but it was too early to measure the magnitude of the spill.

"The river was completely covered with oil from bank to bank," said Beltman, who is evaluating oil pollution in the Amazon for indigenous and peasants suing oil major Chevron Corp (CVX.N: Quote, Profile, Research). "It looked like a bad spill."

The jungle dwellers accuse Chevron of polluting the jungle and damaging their health by dumping 18 billion gallons (68 billion liters) of contaminated water from 1972 and 1992. Chevron denies any wrongdoing.