Expanding the Nord Stream gas pipeline through the Baltic Sea is certain to diversify the regional energy market, the Russian foreign minister said Monday.

Russian natural gas company Gazprom signed shareholder agreements on the development of the second phase of the twin Nord Stream pipeline system last year with its counterparts at German energy companies BASF and E.ON, as well as those from French company ENGIE, Austria's OMV and Royal Dutch Shell.

Under the proposed expansion, two more lines would be added to the existing network, roughly doubling the pipeline's net capacity.

Russian Foreign Minister Sergei Lavrov was quoted by Russian news agency Sputnik as saying the project would be beneficial to the European energy market.

"We are convinced, just like our European partners who are developing this project together with us, that it will help diversity gas routes to the European continent," he said.

European officials have expressed concern about Russia's energy policies in the region, noting Gazprom controls both the supplies and the transit networks that carry them.

Last week, the Polish antitrust authority, known by its acronym UOKiK, confirmed its own suspicions that the project consortium would restrict competition in the Polish energy market. In response, the parties to the project pulled their application to form a company to build and operate the pipeline.

"This will stop the deal," UOKiK President Marek Niechciat said in a statement.

Gazprom started calling for tenders to lay the sections of the planned pipeline in the deep waters of the Baltic Sea earlier this year, adding the additional components could be in service at some point in 2019.

The six parties to the pipeline said in an emailed statement the second phase of Nord Stream is "crucial" to European energy and each company would now work individually to find ways to support its development. The Polish decision, they added, does not impact the continuation of the six-member consortium or the construction of the pipeline, "including its scheduling."