Saudi Arabia's Samref oil refinery said on Sunday all its units were fully operational without exceptions, denying a Reuters report that one unit was down.

"Regretfully, this news is totally incorrect and the refinery is fully operating including all its units without exceptions," Samref said in an emailed statement.

Trading sources told Reuters on Friday that a 155,000 barrel per day (bpd) vacuum distillation unit (VDU) was down, triggering a tender issuance to export residual fuels from the port of Yanbu.

VDUs are used to produce petroleum products from the heavier oils left over from distillation in oil refineries.

Samref on Saudi Arabia's west coast is a 400,000 barrel per day joint refinery between Saudi state-owned Aramco and US oil major Exxon Mobil. – Reuters