Ecuador's state oil firm Petroecuador has been forced to suspend crude exports after a violent demonstration in Napo province shut a key pipeline.
Protesters want a bigger share of oil revenues
Petroecuador's halt to its 144,000 barrels per day (bpd) of exports came into effect on Tuesday after the Trans-Ecuadorean pipeline was closed.
Protesters had occupied a pumping station to demand more state resources for the poor province in the Amazon.
It comes after ongoing Nigerian unrest sent crude prices higher on Monday.
Nigeria's oil exports fell by more than 15% after militants kidnapped nine foreign workers and again attacked facilities in the Niger Delta over the weekend.
The incidents in Ecuador and Nigeria will increase current worries for an increasingly jumpy market.
They come as some Opec ministers say that the cartel may need to cut output - which has been stepped up over the past 12 months to cope with increased demand and pressures on supplies - in the spring.
"The biggest concern is Nigeria's sabotage attacks over the weekend. But other supply concerns, like Opec and Ecuador, are accumulating," said Hiroyuki Kitakata, director at Barclays Capital in Tokyo.
In Ecuador, the affected pipeline ships 380,000 bpd from the Amazon to the port of Balao in the north-west of the country. Petroecuador said the pipeline would be down for 24 to 36 hours.
But a private pipeline with a 500,000 bpd capacity continued operating normally.
The demonstrators want more of the country's oil wealth to be spent on infrastructure and new jobs. They also want a crackdown on alleged corruption by big oil companies.
Ecuador, which is not a member of the Opec cartel of oil producing nations, is the fifth biggest oil producer in South America extracting 532,000 barrels of oil a day.
A total of 37% is extracted by Petroecuador, the rest by private companies.
Last autumn, a protest in the same region stopped Ecuador's daily exports of crude oil for two weeks.
Oil sales account for about a quarter of Ecuador's GDP.