Ecuadorean authorities began arresting shopkeepers for raising food prices as indigenous groups clashed with security forces on Sunday in a fourth day of protests against President Lenin Moreno's austerity measures.

One man died in central Azuay province when roadblocks blocked an ambulance from reaching him after he was hit by a car, authorities said. Local media identified him as a protester, but that could not be confirmed.

Ecuadoreans complain consumer prices have risen sharply as a knock-on effect of Moreno's abolition of fuel subsidies, which has also triggered the nation's worst unrest in more than a decade.

"Everyone's raising prices with the excuse of the gasoline price rise," disgruntled pensioner Camilo Salazar, 65, said at a food market in the coastal city of Guayaquil, where prices have risen by up to a third in just a few days.

The government said 20 people were detained over the weekend for over-charging for products including corn, onions, carrots and potatoes, which are all subject to price controls.

"There is no justification for raising the prices," Interior Minister Maria Romo said in a statement.

Ecuador's dollarized economy had inflation of just 0.27 percent in 2018.

After a two-day strike by transport unions, indigenous groups have taken the lead in demonstrations against Moreno's economic measures. They barricaded roads in various places again on Sunday with burning tires, branches and rocks.

Some protesters threw stones at security forces, who responded with tear gas. The CONAIE umbrella indigenous group published a video showing spear-wielding inhabitants blocking a road and shouting "Down with the government!"

The 66-year-old Moreno won the 2017 election and has set the oil-producing nation on a centrist track after years of socialist rule under predecessor Rafael Correa.