* Six sailors missing after vessel sinks off Sweden

* Chinese-owned ship runs aground, leaking fuel off Norway

* Accidents come after strong gale winds, 4-6 metre waves

(Incorporates NORWAY-SHIP/, adds details, quotes)

By Anna Ringstrom

STOCKHOLM, July 31 (Reuters) - A Norwegian cargo ship sank in a heavy storm in the North Sea off Sweden and its crew of six is missing, rescue workers said on Friday. The Norwegian Meteorological Institute said force 9 "strong gale" winds of 75-88 kilometres per hour (47-54 miles) were registered in the north-western part of the North Sea overnight where the accident took place near the Norway-Sweden border.

Swedish maritime rescue authorities told Reuters that after receiving an emergency signal via satellite, a rescue team found life vests, rafts and debris from the ship but not the six member crew of Norwegian cargo vessel Langeland.

"We have received a message that only wreckage and life-rafts were seen in the area and that the weather has been very poor," Tore Myklebusthaug, managing director of shipowner Myklebusthaug Management, told the NTB news agency.

He said the ship's crew was Russian and Ukrainian. The 70-metre vessel, which went missing close to the Koster Islands, was carrying stone to Norway.

ANOTHER SHIP IN JEOPARDY

In a separate incident about 50 kilometres west of the Koster Islands on the Norwegian coast, a Chinese-owned dry-bulk vessel was leaking fuel after running aground near Langesund.

Norway's Joint Rescue Coordination Centre said 16 sailors had been evacuated from the vessel and seven remained on the ship. The entire crew are Chinese nationals.

"We have put a request to the company (operating the ship) to put pressure on the captain (to abandon the vessel) because Norwegian coast guard reports indicate the ship may not survive," rescue mission spokesman Stein Solberg told Reuters.

He said a helicopter was standing by to evacuate the rest of the crew from the Panama-registered "Full City" vessel, which ran aground without cargo but with up to 1,120 tonnes of fuel on board. It is operated by Hong Kong-based Cosco <0517.HK>.

Television channel TV2 showed pictures of oil coming ashore along the North Sea coastline in southern Norway -- a popular summer holiday area west of the Oslo fjord.

A Norwegian representative of the World Wildlife Fund said the spill could affect a large number of birds from a nearby sanctuary and called on volunteers to help with the clean-up. (Additional reporting by Terje Solsvik, Anna Ringstrom and Wojciech Moskwa)

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