LONDON, May 8 (Reuters) - Royal Dutch Shell said on Thursday part of its oil production in Nigeria remains shut following a spate of sabotage in April to its oil facilities and it still does not know when it can restore the lost production.

"The situation is unchanged," a spokesman with Shell in the Hague said.

About 164,000 barrels of Bonny Light crude production, or about 40 percent of the Anglo-Dutch major's equity oil output in the West African country, was still shut in and a force majeure remained in place.

"Repair works are going on and it is making some progress. But some affected areas are more difficult to access for security reasons so it cannot be done in one day or another," the spokesman said. "We cannot give a specific time frame when repair works will be done."

Production of high quality crude in OPEC member Nigeria has been losing about 560,000 barrels of oil every day from its most recent production level of 2 million bpd.

On Wednesday, oil traders said Exxon Mobil had lifted force majeure on its oil exports from Nigeria as its s output there fully recovered after an eight-day union strike shut all of its output, which averaged 800,000 bpd last year.