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

The Russian oligarch behind the Wagner private paramilitary group fighting for the Kremlin in Ukraine is threatening a mutiny if his forces are not resupplied with ammunition soon.

Yevgeny Prigozhin, owner and curator of the Wagner group, penned a letter to Russian Defense Minister Sergei Shoigue, demanding ammunition be provided to his forces on the battlefield.

In the letter, Prigozhin wrote that if supply problems are not fixed fast, he will complain to Russian President Vladimir Putin and his mercenaries would abandon their positions in Bakhmut, Ukraine, where heavy fighting has been going on for weeks, The Moscow Times reported.

“I appeal to Shoigu with a request to immediately issue ammunition. In case of refusal, I consider it necessary to convey to the Supreme Commander-in-Chief information about the existing problem in order to make a decision and about the advisability of further presence of Wagner PMC in Bakhmut in the conditions of a shortage of ammunition," Prigozhin wrote.

He added, "If the deficit is not replenished ... we will be forced to withdraw part of the units from this territory, and then everything else will crumble. Therefore, the bell is already ringing -- it is called an alarm."

Emphasizing the urgency, Prigozhin noted that Ukraine is planning to launch a counteroffensive soon.

There was no immediate public response from Shoigu or the Kremlin.

"We need to stop deceiving the population and telling that everything is fine with us," Prigozhin wrote. "I must honestly say: Russia is on the brink of disaster. If these screws are not adjusted today, the 'aircraft' will crumble in the air."