One person has died and four are missing from the crew of a cargo ship that sank after colliding with another vessel in the North Sea, German authorities said on Tuesday.

Two further crew members from the ship were rescued after the collision with a second cargo vessel early on Tuesday, German Sea Rescue Society (DGzRS) spokesman Christian Stipeldey said.

The accident happened about 22 kilometres (13 miles) southwest of the island of Helgoland, according to the German Central Command for Maritime Emergencies (CCME).  

Several ships are currently involved in a rescue operation in the area, the agency said. 

The sunken ship was named as the Verity, sailing under a British flag and on its way from Bremen to the UK town of Immingham.

The other ship was the Polesie, under a Bahamas flag and travelling from Hamburg to La Coruna in Spain.

The Verity, owned by the British company Faversham,  was the smaller vessel with a length of 91 metres (almost 300 feet), compared to the Polesie's 190 metres.

The Polesie was still afloat with 22 people on board, the CCME said.

"The emergency services are doing everything they can to rescue the missing people," German Transport Minister Volker Wissing said in a statement.

"My thoughts are with the crew members, their relatives and the rescue teams who have been in action since early this morning."

Two rescue cruisers, an emergency tug, a pilot boat, a police patrol boat and a helicopter were helping with the search, according to the CCME.

"We will not stop the search and rescue operation as long as there is still a small chance of finding survivors," DGzRS spokesman Stipeldey said.

- Rescue operation -

The Polesie is owned by the Polish shipping company Polsteam.

Krzysztof Gogol, a spokesman for Polsteam, confirmed there were 22 crew members on board and said they were uninjured and in "good physical condition". 

Shortly after the collision, the Polesie ship stopped and took part in the search and rescue operation, Gogol said. 

The vessel "took on board one of the crew members of the Verity ship, a Filipino sailor", he said.

A P&O cruise ship that was in the area, the IONA, has also been involved in the rescue operation, according to the CCME.

Helicopters were also involved.

The search was taking place amid "relatively challenging weather conditions", Stipeldey said.

The CCME reported winds of six on the Beaufort scale and waves reaching as high as three metres.

The accident comes weeks after a ship with hundreds of electric cars on board caught fire in the North Sea off the coast of the Netherlands.

The Fremantle Highway was sailing between Bremerhaven in Germany and Port Said in Egypt when the blaze broke out in July.

The accident happened close to Ameland, one of an archipelago of ecologically sensitive islands situated in the Waddensee area.

All 23 crew members were evacuated from the ship, but one person died and several were injured. 

Efforts to tow the ship to shore were complicated by poor weather conditions but it was eventually brought to the northern port of Eemshaven.

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