(IANS) Many areas in Punjab, Haryana, Himachal Pradesh, Jammu and Kashmir and even Chandigarh faced a power blackout early Saturday due to the northern grid 'tripping' owing to heavy fog, affecting rail services.

Railway traffic was adversely affected in Punjab and Haryana due to the power failure but resumed within a few hours.

'It was a difficult situation for both the passengers and the railway authorities. The trains were stranded for nearly three-and-a-half hours due to power failure. But now the situation is under control and rail traffic has been resumed at all the places,' divisional railway manager (Ambala division) H.K. Haggi told IANS.

'In Ambala division, 15 trains got delayed by one hour to three hours 30 minutes. In total, over 50 trains were affected in Ambala, Ferozepur and Delhi divisions.'

The railway authorities have put diesel engines to resume rail services.

'Though at some places we had replaced power-run engines with diesel engines but we do not have diesel engines available at all the places. Moreover, due to the dense fog diesel supply took long time to reach the destination,' Haggi said.

Traffic movement along most highways in Punjab and Haryana was reduced to a crawl due to thick fog engulfing most parts of north India.

'The tripping in the northern grid took place at 3.02 a.m. The snag developed due to thick fog over Punjab and Haryana. Our engineers are working to revive power supply. In some areas, power supply has been partially revived,' Punjab State Electricity Board (PSEB) chairman H.S. Brar said.

The cold wave also intensified with Amritsar and other places recording zero degree temperature.

Met officials said the fog would continue over the region as the dry, cold spell is likely to continue till next week.