ALMATY (Reuters) - Kazakhstan’s biggest oil producer, Tengizchevroil, has restarted operations at its first-generation oil and gas separation plant which had been briefly suspended on Tuesday after a toxic substance was released, the company said.

Chevron, ExxonMobil, Lukoil and KazMunayGas are partners in the venture, which said the event was caused by an unplanned power loss and there were no injuries, spills or equipment damage.

“The power was soon restored and the emissions event stopped,” it said in a statement. “KTL (oil and gas separation plant) start-up is proceeding safely.”

The Central Asian country’s energy ministry said earlier on Tuesday it would investigate the incident, describing it as “emission of toxic substances into the atmosphere”.

The company, which produced 7.3 million tonnes (58 million barrels) of oil in the first quarter, said it had provided the authorized government bodies with information on the event. It did not say what substance had been released.