Angolan April crude cargoes have sold steadily so far with more than half of the program already cleared, but Asian demand is expected to slow down ahead of a heavy refinery maintenance season, trading sources said Thursday.

Activity on the West African crude market slowed down mid-week after a steady start to the week.

Sources said there had been steady activity for Angola's medium sweet grades like Cabinda, Girassol, Nemba, and even for cargoes of the heavier grades like Dalia and Pazflor which struggled in March.

But some traders said activity had slowed down with less buying interest observed from Asia, especially China.

Asia is the main outlet for Angolan crudes, buying almost 60-70% of Angolan crudes every month with China buying almost half of all Angolan cargoes every month.

"The market is a bit slow, I am not optimistic at the moment. We have a very sizeable maintenance season in Asia. A lot of the base-load buying has been covered by term, but with a weaker Middle East crude market. I don't see any support out there," said a trader.

"If you look at the price that some grades like Murban and Qatar Marine were trading at, I don't think WAF grades look that attractive to Asian buyers," he added.

Some sources said that despite an improvement in refining margins, differentials would be not much higher from last month mainly because it was still the maintenance season.

"Margins in general are stronger than last month. But I don't think the market is as high as some offers suggest," said a second trader, "There is some reasonable maintenance in Europe and Asia."