By V. Shankar Ganesh

SHAH ALAM, MALAYSIA: Thirty-one pupils of a school in Bukit Kemuning fell ill and had difficulty breathing after a "gas" leak at the nearby Petronas station at 11am yesterday.

The 31 pupils of SJK (T) Ladang Emerald were rushed to Tengku Ampuan Rahimah Hospital in Klang where they received outpatient treatment.

The Petronas station, located about 300m from the school, was undergoing maintenance.

Teachers said they felt something was not right after they smelled something pungent in the air.

Pupils began complaining of dizziness and some fainted, which led them to be evacuated to the canteen.

Parents were informed and pupils who were not affected were allowed to go home while those feeling unwell were taken to the hospital.

Petronas Gas Shah Alam area manager Mohd Isa Adam denied there was a gas leak.

He said a chemical -- ethyl mercaptan -- a colourless chemical to odorise natural gas, was released during a routine service check at the station.

Petronas Gas Bhd, in a statement released later, also said there was no gas leak at the site.

It said "a small quantity of ethyl mercaptan had escaped into the air at 11.30am during maintenance work at its facility in Shah Alam City Gate".

"The chemical is used to detect any leakage of gas. The smell had drifted towards the school.

"Petronas Gas has taken immediate measures to neutralise the smell of the chemical."

Police and the Fire and Rescue Department cordoned off the road leading to the station during the cleaning-up operations as workers from Kualiti Alam sealed several drums believed to contain the chemical.