A passing snow storm is thought to have sparked a fire in a venting stack at the Bacton gas site in the early hours of Saturday morning.

The flare happened in a 60m tall tower which is used to let unwanted gases into the air at the plant.

But operators have stressed it happened occasionally and was dealt with by one site safety systems, helped by Norfolk fire crews.

It happened at 4.15am in the western section of the giant north Norfolk site run by Petrofac, whose director of southern operations Roy Armishaw said: 'We can reassure local people there was no risk to the local community or of escalation.'

The unit was not actually producing gas at the time, as it was being restarted after a break for routine maintenance.

Staff spotted the fire in the vent and called the fire brigade when the normal 'snuffing' system using nitrogen failed to work first time.

Fire crews from Mundesley, Stalham, North Walsham, Cromer, Wymondham and Hethersett were turned out, but when they arrived a second use of the snuffer worked.

Firemen used thermal imaging camera to check the stack was said Mr Armishaw, who added that engineers thought the flare was because the trickle of methane gas in the stack was ignited by a passing snow storm which contained electro-static discharges.

The incident had not affected the restart of the plant which was still due to be completed at the weekend.

Norfolk Fire Service Group Manager Richard Herrell said the number of appliances sent to the site was a standard response to an incident at the gas terminal. Although the fire was out very quickly crews were on site for more than three hours checking for hot spots. Appliances had to make their way through difficult road conditions on the way to the fire, but had not problems having proceeded with caution.