Two workers of a private cleaning company drowned in a manhole after inhaling poisonous gas while cleaning a sewage outlet at Angsana Mall, here on Sunday.

Ipoh police chief ACP Sum Chang Keong saidinthe 1am incident, the victims Mohamad Ilaala Che Aziz, 27, and Mohamad Nur Syafiq Mohamad Naser, 27, died at the scene.

"Investigations revealed that both the victims and the supervisor were preparing to clean a small outlet leading to the Indah Water Konsortium Sdn Bhd (IWK) plant. They were appointed by Angsana Mall.

"It was found that one of the victims went into the manhole - estimated to be about 20 feet (sixmetres) deep first, by way of sliding down, and then he screamed due to shortness of breath, and another victim went inside to help him," he said in a statement here today.

He added that the autopsy conducted at 11am today confirmed that both victims had drowned.

Meanwhile, Ipoh Fire and Rescue Department chief P.Samasuvamsaid both victims were found stacked on top of each other at the base of the underground channel.

"Both victims were believed to have inhaled poisonous gas found in the underground channel. The hole was very narrow, and we managed to bring out the first victim at about 2.35am and the other, five minutes later," he said.

-- BERNAMA