Protesters confront the police in Quito, Ecuador, on Oct. 9, 2019. The Ecuadorian government Tuesday said it has asked the United Nations to help restore social peace as demonstrations over a fuel price hike intensified. (Str/Xinhua)

Protesters in Ecuador fought a running battle with security forces on Wednesday in a second day of violent demonstrations over a fuel price hike that forced the government to suspend most of the country's deliveries of crude oil.

The violence broke out as thousands of people representing indigenous groups, farmers, students and labor unions marched on a square in Quito's historic center near the government headquarters.

Masked demonstrators threw Molotov cocktails and paving stones. Clouds of tear gas and palls of black smoke from burning tires rose over the colonial downtown area, a UNESCO world heritage site.

After clashes broke out in the area on Tuesday, the government of President Lenin Moreno posted security forces to keep the march from reaching the plaza.

Protesters on Wednesday broke off from the main procession and hurled rocks at riot police, who fought back with volleys of tear gas and water cannon.

The protesters are demanding that Moreno reinstate fuel subsidies that were rescinded after $4.2 billion in loans was agreed with the International Monetary Fund.

"Without a doubt, this is going to be solved very soon," Moreno said in a video broadcast on state television following the day's violence.

The unrest threatened to inflict wider damage on an already weakened economy.

The energy ministry announced it was shutting down one of the country's two domestic oil pipelines, effectively suspending two-thirds of its distribution of crude oil.

"Due to this shutdown, we are analyzing the possibility of declaring force majeure," to avoid the country incurring penalties for postponing crude shipments, the ministry said in a statement.

Protesters seized three oil facilities in the Amazon earlier this week.

Ecuador, which exited the OPEC international oil cartel last week citing economic constraints, produced more than 500,000 barrels per day - which was worth some $4.6 billion in exports in the first six months of the year.

However, Wednesday's shutdown accounts for 68 percent of its oil output, the ministry said, adding that the protests had cost $12.8 million in lost production to date.