Some 12 passengers on a seal watching trip four miles off the coast had to be rescued.

Caister Lifeboat was called out to the vessel carrying nine children and three adults at around 11.42am, on Wednesday June 1.

A spokesman for the independent service said the all-weather boat Bernard Matthews II raced to the scene.

He said the vessel, called Shearwater, had lost power and was in about 2m of water.

The passengers were transferred to the lifeboat and taken to Lowestoft.

Two crew remained with the vessel which was towed back.

The spokesman added he believed it was the service's biggest ever passenger rescue, at least in living memory.

John Kitching of Jet Adventures, which operates trips to the tourist-draw sand bank several times a day, said there was no panic or drama and everything went as it should in a rescue situation.

He said the engine had cut out after a rope got stuck in the impeller and the lifeboat was called.

"It is a very unusual situation and the first time we have been attached to a lifeboat," he said.

"We do actually raise money for Caister so I suppose in a way we are paying for our own tow.

"We were sat watching the seals when it happened."

He added one trip was cancelled as a result of the incident but there was no damage to the boat which had been tested and would be back in action the next day, Thursday June 2.

Guy Gibson, coxswain of Caister Lifeboat, said the crew was able to reach the stricken RIB in around three minutes, as it was on the west side of the bank.

He said the passengers comprised nine children and three adults, most whom thought the rescue added to their day of adventure.

"They were really upbeat," he said.

"They ate all the chocolate we keep on board for the crew. It was a bit of an adventure for them."

However, he said the situation was "precarious" on an ebbing tide which risked the boat running aground and then having to wait until the next high tide to move off the bank.

"It was a different job, and a good job." he said.

Scroby Sands is a haven for seals and clearly marked by a windfarm built in 2004.