Two more oil companies halted output on Tuesday in Libya as unrest sweeping Africa's third-largest producer kept crude prices near a 2-1/2-year high.
A pipeline bringing Libyan natural gas to Italy was also closed and export terminals that ship both crude and oil products were disrupted as violence and confusion gripped a country that pumps nearly 2 percent of world output.
Oil prices, which had surged on Monday, steadied as Saudi Arabia reassured consumers OPEC members would be ready to meet supply shortages, while an official at the International Energy Agency said it was stood ready to release stockpiles in the event of a real disruption.
Several oil companies said they were shutting down operations as they evacuated staff. U.S. oil companies including Occidental Petroleum Corp said production was unaffected.
Spain's Repsol and Italy's Eni said they had shut in production. A day earlier, BASF unit Wintershall confirmed it was winding down output of as much as 100,000 bpd.
The companies did not specify the oil volumes affected but Repsol said it shut the El-Sharara oilfield, which an industry source said pumps about 200,000 barrels per day (bpd) -- 13 percent of Libya's estimated 1.6 million bpd output.
"We have suspended all operations in Libya today because of the violence and uncertainty," said a spokesman for Madrid-based Repsol, which on its website had net 2009 Libyan output at almost 35,000 bpd, the most recent figure available.
Eni said it temporarily stopped some oil and natural gas output. It said none of its Libyan plants and facilities had been damaged.
A number of companies including BP, Royal Dutch Shell and Suncor Energy Inc said they were pulling out staff, but had not confirmed any production impact.
Among U.S. oil companies, Marathon Oil Corp and Occidental said production in Libya continued. Marathon is a partner in the Waha concession, along with ConocoPhillips and Hess Corp.
Schlumberger Ltd, the world's largest oilfield services company, was shutting down operations in Libya. Chief Executive Andrew Gould cited "disturbing" events in Libya, which accounts for 1 percent of Schlumberger's overall revenue.