A man convicted of killing 18 people when he set a public bus on fire in China has been sentenced to death, authorities said.

Ma Yongping, 34, in January set alight the bus in Yinchuan, capital of the remote northern region of Ningxia, leaving 18 people dead and another 32 injured.

He was convicted of arson and sentenced to death by the Yinchuan Intermediate People's Court on Sunday, the city government said in a social media posting.

Ma admitted his actions but said he would appeal against the sentence, according to the government statement.

A college graduate who had studied in Japan, Ma had accumulated more than 300,000 yuan ($46,000) in debts while a contractor on an engineering project, much of it salaries for his workers, according to previous Chinese media reports.

The company refused to pay him, they said, and on the morning of the attack he sent friends a message on chat application WeChat saying: "At a time when even a person's basic rights can't be guaranteed, he has a right to take action to fight for (them)."

Chinese citizens have sometimes turned to violence against innocents in attempts to publicise their plight after failing to obtain redress for low-level disputes.

In 2013, a man started a fire on a vehicle in Xiamen in the eastern province of Fujian, killing 47 people including himself, after writing online he had appealed unsuccessfully to local police 56 times over social security benefits.

Source; AFP