The PCK refinery near the border with Poland is majority-owned by Rosneft Deutschland, a local subsidiary of the Russian oil giant, and managed through a trusteeship by the German government.

While no one was seriously injured as a result of the spill, an environment ministry spokesperson said the crude may have entered local rivers.

"An accident occurred on a PCK pipeline near Gramzow/Zehnebeck... Emergency services are on site. No information can be provided at this time about the cause or the exact extent of the damage," the spokesman said.

State environment minister Hanka Mittelstaedt will visit the site on Thursday morning to assess the damage, he added.

Local newspaper Maerkische Oderzeitung reported that oil was gushing "in a fountain about 10 to 12 metres high" (33 to 39 feet) near the municipality of Gramzow.

At least two refinery employees were "splashed with oil" as a result of the spill, but did not require hospitalisation, a regional fire department spokesperson told AFP.

Around 100 firefighters had been deployed to the scene, and tankers were sucking up the stray oil, another spokesperson at the scene told AFP, insisting the situation was under control.

A spokeswoman for the PCK refinery, which supplies oil to Berlin and the surrounding region, said emergency services, including firefighters and a hazardous materials unit, were on site and trying to contain the damage.

"The safety of all those involved and the protection of the environment are the top priorities," the spokeswoman said.

"According to initial findings, the incident was caused by preparatory work for a planned safety test on the pipeline tomorrow," she added.

"Deliberate external influence can be ruled out at this stage."

Matthias Bruck, a spokesman for the regional environment ministry, said: "We don't yet know the extent of the damage, but we suspect it is very significant."

"We fear that oil may have reached the Welse, a tributary of the Oder" river, he told newspaper Bild, adding that firefighters had deployed floating barriers to contain the spill.

In response to Russia's full-scale invasion of Ukraine, Germany's government placed Russian fossil-fuel behemoth Rosneft's German assets under the trusteeship of the federal energy regulator in September 2022.

But Berlin has struggled to find a permanent solution, and has been forced to extend the trusteeship every six months while it hunts for a buyer.

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