More than 40 people were injured Friday after a disgruntled former employee ignited a petrol bomb at a bank in a Tibetan-inhabited region of northwest China, local authorities said.

The attack in Tianzhu county at 8:00 am (0000 GMT) sparked a fire at the Agriculture Credit Cooperative in Gansu province, according to a statement issued by the county government. Among the injured, 19 are in a serious state.

The former employee, identified as Yang Xianwen, 39, allegedly threw the bomb into a room at the cooperative while a morning meeting was underway, the Tianzhu Tibetan Autonomous County government statement said.

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"Some of the workers at the meeting suffered burns, others were injured after breaking windows and jumping to the roof of an adjacent three-storey building," it said.

Police in the county seat of Huazangsi township -- where the incident occurred -- were investigating the fire and seeking the whereabouts of Yang, who fled the scene, it said.

"In April 2011, Yang Xianwen... embezzled public funds and was fired from the credit cooperative," the government said.

"This incident left hatred in his heart. He started the fire out of revenge and fled the scene."

The official Xinhua news agency had initially said the blast caused "significant deaths and injuries" but later issued a report saying the fire had led to many injuries but no deaths.

About a third of the county's residents are Tibetans. The government statement said the chief suspect was Han Chinese, China's dominant ethnicity.

A travel agent near the scene of the incident told AFP it was unlikely the bombing was related to the local Tibetan population.

"I have not heard anything about this being linked to ethnic Tibetan problems," the agent, a Han Chinese who declined to be named, told AFP by phone. "It could have be due to a dispute at the bank."

Fire engines rushed to the scene early Friday morning but by midday the fire had been put out, she said.

Phones at the Tianzhu People's Hospital, where the injured were taken, went unanswered.

Tensions run deep in Tibetan areas of China, where many Tibetans accuse the government of trying to dilute their culture, and cite concern about what they view as increasing domination by China's majority Han ethnic group.

That tension erupted in violent demonstrations in March 2008 in Tibet's capital Lhasa, which then spread into neighbouring Tibetan areas of China, including Gansu.