The fire is believed to have broken out in the scaffolding and then spread to the main building.  [AFP]

At least 53 people have been killed and 70 others injured after a huge fire broke out in a Shanghai building, sending plumes of black smoke billowing across the city, the official Xinhua news agency has reported.

The 30-storey building was being renovated when it caught fire about 2pm local time (0600GMT) on Monday, Chinese state media said, quoting witnessess who said they had seen people jumping from the windows of the blazing building.

More than 80 fire engines were at the scene trying to bring the fire under control, Chinese television said.

It took firefighters four and a half hours to extinguish the blaze. The cause of the blaze is unclear, but construction scaffolding around the building caught fire first, and flames then spread to the main building, which has about 500 apartments.

Inquiry set up

The government would thoroughly investigate the fire and punish anyone responsible, Public Security Minister Meng Jianzhu was quoted as saying by Xinhua. The State Council, or cabinet, has set up an investigation team.

Survivor Li Xiuyun, 61, said she fled down the steps of the building with her husband, son and a granddaughter from their home on the 16th floor until they met up with firefighters who took them to safety.

"The smoke was very strong and the glass of the windows was scalding," she told AFP at the Jingan District Hospital, adding that she cut her feet on glass when fleeing.

"My son took off his socks and soaked them with water, and we used them to cover our noses. I stumbled on people on the floor when walking."

The Jingan District Hospital said it had taken in 55 injured victims of the fire, nine of whom were in serious condition, according to state television reports.

Al Jazeera's Melissa Chan, reporting from Shanghai, was unable to confirm reports of people leaping from the building's windows. "State media are reporting that, but we have no photographic evidence of it," she said.