Police in China are investigating after 15 boxes filled with live snakes were found on a bus, state media reported on Saturday.

The snakes were packed alongside containers holding toads and rats in the luggage compartment of a coach in central China's Hubei province, the official Xinhua news agency said.

Many of the vehicle's 53 passengers were "terrified" and ran away when the animals were discovered, 200 km into the coach's journey, it added.

Xinhua said transportation of live animals must be approved by Chinese transport and quarantine authorities, adding that the driver of the coach failed to show police certificates granting permission.

An investigation is underway, the news agency said.