An explosion at a coal mine in China's central Henan province has killed at least 42 workers and left another 44 miners trapped, officials have said.

The country's work safety watchdog said the pre-dawn explosion occurred at Xinhua No 4 pit in Pingdingshan city on Tuesday.

The State Administration of Work Safety in a statement on its website said 14 of the 93 men who were working underground at the time of the blast managed to escape.

It did not say what caused the explosion.

China's mines are the deadliest in the world, with unregulated mines accounting for almost 80 per cent of the country's 16,000 mines.

An average of 13 workers are killed every day in the country, with most accidents blamed on lax safety standards and a rush to feed demand from a robust economy.

Despite pledges by the Chinese government to improve safety, regulations are poorly enforced while the country's soaring demand for energy and resources often means many unsafe mines continue to operate.

In 2008 alone more than 3,000 people died in coal mine accidents across China.