KIEV: Ukrainian President Volodymyr Zelensky warned German Chancellor Angela Merkel Sunday that the soon-to-be completed Nord Stream 2 pipeline carrying Russian gas to Europe was "a dangerous geopolitical weapon".

The comments came as the two leaders met in Kiev for a last time ahead of Merkel leaving office after 16 years in power next month and days after she held final talks with Russian President Vladimir Putin in Moscow.

Bypassing Ukraine and depriving the Western ally of essential gas transit fees Kiev estimates to be at least $1.5 billion per year, Nord Stream 2 is set to double Russian natural gas shipments to Germany, Europe's largest economy.

Kiev fiercely opposes the pipeline, arguing that it will increase Europe's energy dependence on Russia and Moscow's geopolitical clout.

"We view this project exclusively through the prism of security and consider it a dangerous geopolitical weapon of the Kremlin," Zelensky said during a joint press conference with Merkel.

While the main risks after the completion of the $12-billion pipeline beneath the Baltic Sea would be "borne by Ukraine", he said, it would also be dangerous "for all of Europe".

Merkel said Berlin agreed with Washington that "gas must not be used as a geopolitical weapon.

"It will come down to if there is an extension to the transit contract via Ukraine - the sooner the better," she said, referring to the expiry of Moscow's agreement with Kiev in 2024.

'A special responsibility'

While the construction of the pipeline led to tensions between Germany and the United States, Washington eventually waived sanctions against the Russian-controlled builder of the pipeline.

Merkel on Sunday sought to reassure Zelensky, saying that the Germany-US agreement specified "sanctions" if gas was "used as a weapon".

These commitments are "binding on future German governments", she noted.

She also said she had discussed with Putin extending Russia's transit contract with Ukraine past 2024.

"We feel a special responsibility" and "understand the big concerns that President Zelensky expressed," she said. "We take them very seriously."