UPDATE 1-Nippon Oil sees May crude refining down 6 pct y/y

* May to mark 7th month of yr/yr declines in refining

* Refining seen down around 250,000 kl yr/yr in May

* 180,000 bpd Muroran refinery maintenance from May 14

TOKYO, April 24 (Reuters) - Nippon Oil Corp 5001.T said on Friday it was likely to refine around 6 percent less crude oil in May than it did a year earlier, marking a seventh straight month of declines, reflecting slow domestic demand amid the recession.

Nippon Oil, Japan's biggest refiner, is likely to refine around 250,000 kilolitres less crude next month compared with a year earlier, a company spokesman said. The refining volume is seen around 4.17 million kl (845,000 barrels per day), according to Reuters calculations.

Still, the plan marks a slight recovery after curbing refining by more than 10 percent in the six months to April. The company spokesman said there were signs of a recovery in demand for gasoline and petrochemicals.

Nippon Oil plans to refine 3.65 million kl (765,000 bpd) in April, which would be down 23 percent from a year earlier and marking the sixth straight month of curbs of over 10 percent.

The company also said it plans to conduct scheduled maintenance on its 180,000 barrels-per-day Muroran refinery for about a month from May 14.

Industry sources had expected maintenance on the northern Japan refinery to be conducted from May 7 to June 27. (Reporting by Osamu Tsukimori; Editing by Chris Gallagher)