FIVE people were killed and six were missing after a helicopter carrying workers from a North Sea gas field plunged into the sea 30 miles off the East Anglian coast.

FIVE people were killed and six were missing after a helicopter carrying workers from a North Sea gas field plunged into the sea 30 miles off the East Anglian coast.

Eleven people were on board the aircraft, two of them crew and the rest oil rig workers when the aircraft came down off Cromer.

It is not yet known why the helicopter went down and a spokesman for RAF Kinloss, north Scotland, which is helping co-ordinate the rescue, said weather conditions were good.

A spokesman for RAF Kinloss said five bodies had been recovered from the water.

He said six people remained missing and the search would continue with an RAF Sea King helicopter from Wattisham Airfield and seven boats, including two rig support vessels and a mixture of lifeboats and coastguard fast response boats.

The recovered bodies have been taken back to the Santa Fe Monarch rig as it was closer to the accident scene.

Great Yarmouth coastguards, co-ordinating the rescue operation, said the helicopter was taking workers from the rig when it ditched about 30 miles off Cromer around 7.50pm yesterday.

The spokesman for RAF Kinloss, which is home to the Aeronautical Rescue Co-ordination Centre, said the craft was a Sikorsky S76, which carried around a dozen people.

It was too early to say what caused the accident, he said, adding: "The weather was quite benign, there was good visibility and light winds.

"There is no indication at this stage that any other aircraft were in the area at the time."

A spokesman for the East Anglia Ambulance NHS Trust in Norfolk said: "We have senior officers at strategic points throughout the north of the county.

"We have crews on standby and will await news from the coastguard."

He added that the James Paget hospital in Gorleston had been alerted.

Flt Sgt Adrian Osbourne, from Wattisham Airfield, said only one search and rescue aircraft would be involved in the rescue operation because coastguards had pinpointed the exact location of where the helicopter entered the water.

"The aircraft which ditched into the water is floating. The crew is wearing night vision goggles but the light was failing them. The helicopter is fully equipped with life jackets and lights," he said.

"This will be a routine flight for the crew and they train for this every day."

Mr Osbourne added the search was expected to continue through the night with the rescue helicopter refuelling at Norwich Airport.

A coastguard spokeswoman said four vessels responded to the coastguard mayday relay and were also searching for survivors.

Yarmouth Coastguard Watch Manager Mario Siano said: "The weather for searching is good at the moment with five-mile visibility and slight seas."

The helicopter involved in the crash is believed to be owned by Bristow, which provides helicopter transportation services in the North Sea and specialises in the movement of personnel to offshore production platforms and drilling rigs.

It also provides search and rescue services and military rotor wing training.

The company has a fleet of more than 120 aircraft, including the world's largest commercial fleet of the 18-passenger helicopter Super Puma, a harsh-environment-style aircraft.

The southern area of the North Sea is serviced from facilities in the south east of England and Holland using medium sized 12-passenger aircraft.

This area draws support, materials and operational assistance from the company's headquarters in Redhill, Surrey.