Russia said Monday it will extend the Black Sea Grain Initiative after it expires on March 18, but only for 60 days. The announcement came after consultations between U.N. representatives in Geneva and Russian Deputy Foreign Minister Sergei Vershinin.

"The Russian side, noting the package nature of the Istanbul agreements proposed by UN Secretary General António Guterres, does not object to another extension of the Black Sea initiative after the expiration of the second term on March 18, but only for 60 days," Vershinin said, according to Russian media reports.

Russia's consultations in Geneva on the grain deal were not easy, Vershinin said. Russia will rely on the effectiveness of the implementation of the agreement on the export of its agricultural products when deciding on a new extension of the grain deal, according to reports.

Ukraine, which is a key world exporter of wheat, barley, sunflower oil and fertilizer, had its shipments blocked in the months following the invasion by Russia, causing a worldwide spike in food prices. The first deal was brokered last July.

Russian forces suffered more than 1,100 dead in less than a week during battles near the eastern Ukrainian city of Bakhmut, the focal point of fighting in eastern Ukraine, President Volodymyr Zelenskyy said on Sunday.

During his nightly address, Zelenskyy described the battles as "Russia's irreversible loss."

Russian forces also sustained about 1,500 "sanitary losses," meaning soldiers were wounded badly enough to keep them out of further action, Zelenskyy said.

Dozens of pieces of enemy equipment were destroyed, as were more than 10 Russian ammunition depots, Zelenskyy said.

-ABC News' Edward Seekers

The investigation into who was behind the Nord Stream natural gas pipeline explosion should be "objective, impartial and transparent," Russian Foreign Minister Sergei Lavrov told Russian news agency Interfax.

"I do not want to threaten anyone. I do not want to hint at anything either. I just know that this flagrant terror attack will not go uninvestigated," Lavrov added.

Russia also said it will distribute its correspondence with Germany, Denmark and Sweden on the investigation of the Nord Stream explosion among the members of the United Nations Security Council soon.

Russia claimed the three countries are denying Russia access to information and participation in the investigation, first deputy permanent representative to the U.N. Dmitry Polyansky said in an interview, according to Russian news agency TASS.

-ABC News' Anastasia Bagaeva and Tanya Stukalova

Ukrainian President Volodymyr Zelenskyy denied that Ukraine had anything to do with the Nord Stream gas pipeline explosions last year.

"As for the Nord Stream, we have nothing to do with it," Zelenskyy said Friday.

The New York Times published a report that U.S. intelligence suggests that a pro-Ukrainian group sabotaged the pipeline.

Zelenskyy also suggested that the information being spread about the involvement of pro-Ukrainian groups in the attack could be done to slow down aid to his country.

-ABC News' Natalia Shumskaia

A Moscow court has sentenced one of Russia's best-known opposition leaders, whose family live in the U.S., to 25 years in prison in what is widely seen a show trial.

Vladimir Kara-Murza is the most high-profile opponent of Russian President Vladimir Putin to be jailed since Alexey Navalny.

Kara-Murza's extraordinarily harsh sentence is one of the lengthiest any opposition figure has received under Putin and illustrates how repressive Russia has become during the war in Ukraine, reverting to something much closer to the USSR where no opposition is tolerated.

Kara-Murza was convicted of treason, as well as "discrediting Russia's armed forces," a new law that effectively criminalizes criticizing the war in Ukraine. He was also convicted of belonging to a banned organization. The charges are widely seen as politically motivated.

Kara-Murza is one of Russia's best-known pro-democracy figures and a veteran critic of Putin.

Kara-Murza, who holds both British and Russian citizenship, spent many years living in the United States and his wife and children still live in Virginia. He was close to the late U.S. Sen. John McCain, who championed human rights in the former Soviet Union.

Dozens of journalists and Western diplomats attended the court hearing on Monday, including the U.S. ambassador who read out a statement condemning the sentence.

"We support Mr. Kara-Murza and every Russian citizen to have a voice in the direction of their country. Mr. Kara-Murza and countless other Russians believe in and hope for a Russia where fundamental freedoms will be upheld. And we will continue to share those hopes and work for that outcome," Amb. Lynne Tracy said.

Kara-Murza previously has survived being poisoned not once but twice. In 2015 and then again in 2017, he suffered organ failure after being exposed to an unknown toxin. Independent researchers later linked the poisoning to the same team of FSB poisoners who targeted Navalny.

He chose to return to Russia after the war began, believing it was important to continue to campaign for freedom in his country and has been an outspoken critic of the invasion.

His trial was held entirely behind closed doors, but a letter containing his closing statement to the court has been released to reporters.

"I only blame myself for one thing," Kara-Murza said in the statement. "I failed to convince enough of my compatriots and politicians in democratic countries of the danger that the current Kremlin regime poses for Russia and for the world."

"Criminals are supposed to repent of what they have done. I, on the other hand, am in prison for my political views. I also know that the day will come when the darkness over our country will dissipate.

-ABC News' Patrick Reevell