The well, which is owned by Total, was the subject of a £1m fine after another leak in 2012

Questions need to be asked about safety and protection of the environment, campaigners have said, after a leak in a North Sea well being drilled by the oil and gas firm Total.

The company may be forced to temporarily abandon part of the well owing to a gas leak beneath the seabed, which has restricted access to the wellhead at its Elgin B platform.

“Protecting staff and the marine environment should always be priority number one for the oil and gas industry. Given the previous problems at this site, serious questions need [to be] asked by the relevant authorities as to what is going on,” said WWF Scotland director Lang Banks.

“This is a worrying development, as this is the not the first time Total has had problems at its Elgin-Frankin field. Only a few years ago, a leak on its platform complex led to an emergency evacuation and a halt to production for almost a year.”

The company was fined a record £1.125m after one of the North Sea’s biggest gas leaks in 2012.

The current leak occurred as workers drilled more than 4,000 metres (13,123ft) below the seabed. Total said the well remained “under full control” at the surface. Only staff involved in drilling the well are now allowed on to the wellhead platform, while the wells from Elgin B have been shut down.

A Total spokesman said: “Total has encountered difficulties whilst drilling a well on its Central Graben asset. The well remains under full control at the surface and the situation is under continuous review.

“Wireline measurements carried out inside the drill string indicate some flow exists within the well, which means part of the well may need to be plugged and abandoned.”