LISBON- The atmospheric distillation unit at Portugal's 225,000-barrel-per-day Sines oil refinery owned by Galp Energia GALP.LS has been in an unplanned outage since the beginning of last week, the company said.

It said it expected no supply disruptions in the Portuguese market.

In a filing issued late on Friday, Galp said that, due to an "unplanned event in one of the furnaces" it had shut down the unit, which, after restart, was expected to operate at lower run rates for some weeks.

"The conversion units are operating under normal conditions. Galp will continue to supply its customers, with no expected disruptions in the Portuguese market," it said, without mentioning any potential impact on sales abroad.

After Galp closed a small refinery in Matosinhos in April, the Sines refinery is the only operating in Portugal and one of the largest in Iberia. Last year, exports accounted for 35% of oil product sales.

(Reporting by Sergio Goncalves, editing by Andrei Khalip; editing by John Stonestreet) ((sergio.goncalves@thomsonreuters.com; +351213509204; Reuters Messaging: sergio.goncalves.reuters.com@reuters.net))