Chinese police have identified a suspect who might be responsible for the fire that gutted a commuter bus, killing 47 and injuring dozens more during rush hour in the southeastern port city of Xiamen.

Investigators said early on Saturday that the fire appeared to be intentionally set, and not an accident, the state news agency Xinhua reported.

Xinhua also said that in addition to the 47 dead, 34 people remained hospitalised.

Xiamen police did not provide further details about the identity of the suspect.

The fire ripped through the bus during the Friday evening commute while it traveled on an enclosed and elevated road in the city.

A local fire official said emergency responders found bodies piled inside the charred, skeletal bus.

Investigators said early Saturday that the fire appeared to be intentionally set, and not an accident, Xinhua reported.

Investigators reportedly found traces of gasoline on the wreckage, though the bus ran on diesel fuel and its oil tank and tires remained intact.

Serious criminal case

"It's a serious criminal case,'' the Ministry of Public Security, the national police agency, said in a statement on its website.

Xiamen, a prosperous trading port known for centuries in the West as Amoy, was rattled by Friday's fire.

The city immediately suspended service of the entire express bus system, known as Bus Rapid Transit, but operations resumed on Saturday morning.

Witnesses quoted by Xiamen's official news site said they heard sounds of explosions after the fire had been burning for 10 minutes. Photos posted online showed heavy black smoke curling from the burning bus on the elevated road.

The incident took place just days after 120 people died in a fire at a poultry plant in the province of Jilin.

Authorities said safety management at the plant was a "total mess" and have detained two senior executives.

Buses have been targeted before in China.

In 2009, a passenger ignited gasoline on a bus in southwestern Chengdu, killing 27 and injuring dozens more.

Another 24 people died the same year in a shuttle bus fire in Wuxi, near Shanghai, started by a disgruntled steel worker.

In 2005, a 42-year-old farmer with terminal lung cancer set off a home-made bomb aboard a bus in southeastern China, in a suicide attack that wounded 31.

Source: Agencies