WARSAW (Reuters) - Poland’s anti-monopoly office has launched proceedings against Russia’s Gazprom and five European firms responsible for financing the planned Nord Stream 2 natural gas pipeline over potential breach of anti-monopoly laws, the office said on Wednesday.

Poland sees the Nord Stream 2 gas pipeline, which would double Russia’s gas export capacity via the Baltic Sea, as a threat to Europe’s energy security and argues it will strengthen Gazprom’s already dominant position on the market.

Warsaw is still buying most of its gas from Russia, but has reduced this reliance thanks to a new LNG terminal and supplies from other sources.

In 2016, Polish watchdog UOKIK said the Nord Stream 2 project would undermine competition and did not agree on a joint venture between Gazprom and its European partners, which include Uniper, Wintershall, Shell, OMV and Engie.

“Two years ago, the company that was supposed to construct the Nord Stream 2 gas pipeline was not cleared for this transaction,” the watchdog’s chief was quoted as saying in a statement.

“Unfortunately, the entities decided to finance this project despite UOKIK’s objection. This may constitute a violation of anti-monopoly law and that is why we put the allegations to Gazprom and five other entities,” he said.