Sri Lankan authorities have deployed troops near petrol stations as sporadic protests erupted among the thousands of motorists who queue for scarce fuel daily, AFP reported.

Sri Lanka is battling the worst economic crisis in over 70 years, with constant power outages and shortages of essential goods such as food and cooking gas.

The soldiers were deployed after an angry mob blocked a main artery in Colombo and delayed traffic for hours because people were unable to buy kerosene on Monday, government spokesman Ramesh Patirana said.

Footage of the incident shared on social media shows a group of angry women blockading a tour bus to protest a shortage of kerosene needed for cooking.

The troop deployment also followed the killing of a motorcyclist by another driver after a dispute over his place in a long fuel line outside Colombo.

The mood is getting worse as the lines get longer, a senior Defense Department official told AFP on condition of anonymity.

Police said three elderly people had dropped dead in line for fuel since Saturday, adding that at many gas stations people pitched tents overnight to wait for diesel and gasoline to be bought.

Military officials said the soldiers were deployed to the pumping stations of state-owned Ceylon Petroleum Corp, which accounts for two-thirds of the fuel retail business in the country of 22 million people.