Editor’s note: This story has been updated from a previous version posted at 7:56 a.m. CT on Jan. 6.

Oil production at Kazakhstan’s top field Tengiz was reduced on Jan. 6, its operator Chevron said, as some contractors disrupted train lines in support of protests taking place across the central Asian country.

Demonstrations in the west of the country against a New Year’s Day fuel price hike have quickly grown into deadly anti-government riots with Russia sending in paratroopers to put down the countrywide uprising.

Kazakhstan is a major oil producer with output of about 1.6 million bbl/d in recent months, and has rarely seen production disrupted by unrest or natural disaster.

“TCO production operations continue, however, there has been a temporary adjustment to output due to logistics,” Chevron, the largest foreign oil producer in Kazakhstan with a 50% stake in the Tengizchevroil (TCO) joint venture, said in a statement.

Protestors at the field have disrupted train activity which is used to export oil, sources told Reuters.

TCO produces around 700,000 bbl/d. It was not clear by how much output has been reduced. Other top fields in Kazakhstan are onshore Karachaganak and offshore Kashagan.

Besides Chevron, the three key projects involve most top foreign companies including Exxon Mobil, Lukoil, Royal Dutch Shell, Eni, TotalEnergies, CNPC and Inpex.

A Shell spokesperson said production at the Karachaganak and Kashagan ventures was continuing.

“We are following developments in Kazakhstan closely. We are focusing on keeping our people and operations safe, working closely with our venture partners... We are keeping the situation under constant review.”