NEW DELHI (AFP) - At least 21 revellers were killed en route to a wedding when their truck flew off a bridge, police said on Wednesday (April 18), the latest horrific crash on India's accident-prone roads.

The truck, carrying more than 40 passengers, smashed through a protective railing in central Madhya Pradesh state late on Tuesday and plunged nearly 20 metres to a dry riverbed below.

Police in Sidhi district said 21 people were injured, most of them critically, in the accident some 560 kilometres from the state capital Bhopal.

"Several teams of police and emergency services were rushed to rescue the injured. Most of the injured were in a critical condition," local police officer Vishal Sharma told AFP.

The immediate cause of the accident was unknown, but Mr Sharma said the driver was likely speeding.

India has some of the world's deadliest roads with more than 200,000 fatalities annually, according to the World Health Organisation.

Last week, at least 30 people, including 27 children, were killed in northern Himachal Pradesh state when a school bus plunged off a cliff.
The next day, 18 people were killed when a truck packed with labourers overturned on a highway in western India.

Most accidents are blamed on poor roads, badly-maintained vehicles and reckless driving.

Commercial drivers are largely unregulated, meaning many work long hours through the night, raising the danger of them falling asleep at the wheel, campaigners say.