Smoke wafted from a room at the back of Carlton Hotel in Bras Basah Road yesterday afternoon, with witnesses saying they heard several loud explosions from the premises.

The Singapore Civil Defence Force (SCDF) told The Straits Times that it responded to the fire at 1.15pm.

Electricity and gas supply company SP Group later confirmed that equipment failure at the substation serving Carlton Hotel led to an electricity flashover, or an abnormal electrical discharge. The flashover caused the fire.

The equipment failure also caused a power outage in several parts of central Singapore.

While supply was restored to most areas by 1.21pm, the hotel remained affected until 6.34pm.

In a Facebook post, Carlton Hotel said that no part of the hotel was damaged as the fire was contained within the substation.

"As the SP substation is located on the ground floor of our hotel, for the safety of all our guests, we initiated an evacuation of everyone in the building," the hotel said.

"We apologise for the inconvenience caused."

While supply was restored to most areas by 1.21pm, the hotel remained affected until 6.34pm.

Public relations executive Jonathan Lim, 32, who was in Odeon Towers, which is next to the hotel, said that the lights and the air-conditioning in his building were affected by the outage.

He went out of the building and saw smoke coming out from a door at the back of Carlton Hotel.

The door appeared to lead to a room containing power supply equipment, he said.

"I was a bit shocked and alarmed. We saw some metal on the floor near the area," Mr Lim said.

There was also a strong smell of burning plastic, he added.

Onlookers told him that they heard an explosion earlier.

He later heard a second explo-sion as he was waiting outside the building.

Photos of the incident showed two fire engines and several SCDF officers at the scene.

In an update on Facebook at 3.15pm, SCDF said that the fire was contained within a switch room and about 1,000 people were evacuated from the building.

The fire was put out using extinguishers, and there were no reported injuries, SCDF said.