LONDON, June 14 (Reuters) -Sales of medium Nigerian grades are picking up for July, a trader said on Friday, with the African country having sold off most of its June hangover.

* Light sweet crudes, such as those on offer from West African countries, are losing out to competition from similar U.S. crude streams in Europe, traders have said.

* But expectations for a stronger market are growing going into late July loading to capitalise on the summer driving season. The pace of sales for July loading is better than June, the trader said on Friday.

* However, sales of July-loading grades are being held up by buy tenders, including from Indonesia's Pertamina.

* Separately, Nigeria's huge and strategically important Dangote refinery, which is designed to wean the country off fuel imports, is facing a delay in producing diesel.

* Gasoline deliveries are delayed until July from the previously planned May, Aliko Dangote told Nigerian media this week.

Reporting by Natalie Grover in London; Editing by Alexander Smith

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