(Reuters) - Uniper UN01.DE deliberately obstructed Fortum's proposed purchase of a stake in the German utility by registering assets in Russia as strategic, Kommersant daily quoted Fortum FORTUM.HE CEO Pekka Lundmark as saying on Thursday.

FILE PHOTO: Pekka Lundmark, President and CEO of Finnish utility company Fortum, poses after a news conference announcing that Fortum is set to gain control of Germany's Uniper by acquiring the stakes of activist funds Elliott and Knight Vinke in Duesseldorf, Germany, October 8, 2019. REUTERS/Thilo Schmuelgen

Uniper and Fortum have had a strained relationship since the Finnish state-owned company launched a takeover bid for the German group in 2017 which Uniper opposed.

In October, state-controlled Finnish utility Fortum agreed to buy a stake of more than 20.5% in Uniper, which would bring its total holding to more than 70.5%.

But the purchase is subject to Russian regulatory approval due to a strategic water license operated by the German group's Russian subsidiary Unipro UPRO.MM.

“The company registered water supply activities at Surgutskaya GRES-2 as a natural monopoly on (its) own initiative after we announced our offer to buy Uniper shares,” Lundmark told Kommersant.

Lundmark said Fortum had discussed the issue with the Federal Antimonopoly Service of Russia, and the regulator is considering Fortum’s application to buy the stake.

Uniper’s Russian business Unipro does not plan to classify assets at its other four power stations in Russia as strategic, Interfax cited Unipro official Dmitry Ermilichev as saying on Thursday.

“We have such a theoretical possibility at all five of our power plants, but we are not considering it and we are not planning such actions”.

Earlier Interfax quoted Ermilichev as saying that Unipro was considering such a move.

Fortum said in a separate statement it expected to close the deal by the end of the first quarter in 2020. Lundmark also said Fortum would seek to chair Uniper’s supervisory board once the deal closed.

Alexander Chuvayev, head of Fortum’s Russian business, said the company hoped the Russian state would find a solution so the acquisition of Uniper could go ahead.

He said while Unipro had the possibility to assign strategic status to its operations in Russia, there was no need to do so.

He also said it would be possible to divest Unipro’s strategic operations to facilitate the deal.

Uniper said earlier this month that Fortum had yet to address a range of questions about its intentions in the takeover talks to get management support for any deal.