A strong odour that wafted across the city on Friday created panic among citizens.

Residents of Maryhill first reported the odour in the morning. People from other areas said it seemed cooking gas had leaked somewhere. Many checked their LPG cylinders.

Residents of Mallikatte reported it at 1pm, and those of Maroli at around 1.30.

When contacted, officials of the Karnataka State Pollution Control Board (KSPCB) said they set out at 2pm with the VOC (volatile organic compound) meter to check the levels and detect the source.

Environment officer N Laxman said: "The smell was strong near New Mangalore Port at 50 parts per million. When we proceeded towards the city, it subsided and recorded zero level. We got complaints from the Maroli area; but by the time we reached, there was no trace."

An official of a petroleum company said that it could be due to vapour rising from the seabed due to a depression. Such a phenomenon was noticed in parts of Kasaragod a few years ago.

Another source said that it could be a leak from an LPG bottling unit at Baikampady, very close to the Pollution Control Board office.

MRPL officials said they sent environment engineers to assist the KSPCB to identify the gas.

KSPCB sources said the odour could be that of gas that leaked from a moving tanker, but petroleum company officials discounted this.

Fire officials were on guard at strategic points in the city and on the national highway to trace the source of a possible leakage.