OSLO, April 16 (Reuters) - Norway's Nyhamna gas processing plant gradually ramped up exports on Tuesday following successful repairs of a faulty valve on the North Sea gas transportation hub Sleipner Riser, system operator Gassco said.

Nyhamna, one of Europe's biggest gas processing hubs, shut almost all production late on Sunday and on Monday when a Sleipner valve did not tighten as planned, Gassco had previously said.

"The repairs of the valve at Sleipner went very well and the work was completed last night," a Gassco spokesperson said on Tuesday. "Nyhamna has been ramping up since this morning."

Overall output capacity at Nyhamna was expected to amount to around 24 million cubic metres (mcm) of gas on Tuesday, up from 10 mcm on Monday but still well below the plant's 79.8 mcm overall capacity, Gassco said in a market message.

The outage was expected to end by early Wednesday morning, the operator added. (Reporting by Nora Buli, writing by Terje Solsvik, editing by Stine Jacobsen and Anna Ringstrom)