A heroic French tourist saved a bus of 22 people from plunging down a cliff in the Austrian Alps.

The 65-year-old man was one of 21 French passengers on board the bus, which was travelling along the Tyrolean Alps when the 76-year-old driver fell ill and collapsed, police say.

The bus had driven into a barrier on the road before coming to a stop, and four people were taken to hospital. There were no fatalities.

The passenger had been sitting close to the driver when he collapsed on a road near the city of Schwaz in western Austria.

The vehicle then careened through the wooden roadside guardrail, prompting the Frenchman to jump from his seat and wrench the brake, local media report.