State-owned Bahrain Petroleum Co (BAPCO) partially shut down production due to staff shortages caused by political unrest in the kingdom, trade sources said.
It was unclear how much output was affected at the refinery, which has capacity of more than 250,000 barrels per day of crude, and BAPCO officials were not immediately available for comment.
"There has been a partial shutdown at BAPCO because of a shortage in staff due to the protests going on," said one Bahrain-based trader.
"If things continue I think we will be seeing a rise in price of products, because at this point we don't know when the staff will return to work," another Bahrain-based trader added.
Traders had told Reuters on Wednesday the large 267,000 barrel per day (bpd) state-run BAPCO refinery was partially shut for planned maintenance.
For now traders were also uncertain about the volumes of products being exported.
"This staff problem happened today and the impact won't be felt right away, and the ports are still open so we just have to wait a few days to get more details on the situation," a Gulf-based trader said.
Bahrain arrested at least six opposition leaders, a day after its crackdown on protests by the Shi'ite Muslim majority drew rare U.S. criticism and raised fears of a regional conflict.