LONDON — Ukraine stopped the flow of Russian natural gas through its territory to Europe at 7 a.m. on Wednesday, as a long-held deal expired, Kyiv officials said.

“We stopped the transit of Russian gas, this is a historic event,” Herman Galushchenko, Ukraine’s energy minister, said in a statement. “Russia is losing markets, it will suffer financial losses.”

The move had been expected, as Galushchenko and other officials signaled they were preparing to stop the transnational pipelines and discussing the move with neighboring nations.

“We have undergone a series of stress tests of our gas system in order to be sure that after the transit is closed, we will be able to function stably, ensuring gas supply to consumers,” Galushchenko said on Ukrainian TV last week, according to his office.

Natural gas exported by Russia through Ukraine has long been used by European countries, including Slovakia, which had pushed for Ukraine and Russia to reach a deal to continue the transit.

Russia’s gas giant Gazprom confirmed the stoppage, telling state-affiliated TASS news agency that Kyiv had refused to extend the transit deal.

“The supply of Russian gas for its transportation through Ukraine stopped at 8:00 a.m. Moscow time,” Gazprom said in a statement, according to TASS.

The deal had provided for about 40 billion cubic meters of Russian gas to transit through Ukrainian territory each year, according to TASS.