Several people are missing after a collision between two cargo ships in the North Sea, one of which is believed to have sunk, German authorities said on Tuesday.

The accident happened early on Tuesday morning about 22 kilometres (13 miles) southwest of the island of Helgoland, the German Central Command for Maritime Emergencies said.

Several ships are currently searching for survivors in the area, it added.

One person was rescued from the water and is receiving medical treatment.

The ship that is believed to have sunk was named the Verity, sailing under a British flag and on its way from Bremen to the British town of Immingham.

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

The Verity 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 agency said.

Two rescue cruisers, an emergency tug, a pilot boat, a police patrol boat and a helicopter are helping with the search.

A cruise ship that was in the area has also been involved, the agency added.