Sixty miners have been killed in a blast inside a coalmine in China's Henan province, according to officials.

Eighty-eight workers are stranded inside the Daping mine and their "condition is still unknown", the official Xinhua agency quoted a rescuer at the site.

There is a small chance that the stranded miners will be rescued, the Deputy director of the State Administration of Work Safety, Sun Huashan, said citing past experiences.

Over 1,000 people are involved in rescue operations, the officials said.

More than 400 miners were at work when the blast occurred on Thursday night after the gas density in the mine rose from 1.49 per cent to 40 per cent in just over two minutes.

Located under the Songshan mountain 40 km southwest of Zhengzhou city, the state-owned mine has 4,100 employees.

Put into operation in 1986, the mine has an annual production capacity of 1.3 million tonnes.