UNITED NATIONS - United Nations Secretary-General Antonio Guterres on Monday expressed his deep concern over Russia's decision on the status of Donetsk and Lugansk of Ukraine.

The secretary-general is "greatly concerned" by the decision by the Russian Federation related to the status of certain areas of Donetsk and Lugansk regions of Ukraine, said Stephane Dujarric, spokesperson for the UN chief.

Through a statement attributable to Dujarric, the UN chief called for "peaceful settlement" of the conflict in eastern Ukraine, in accordance with the Minsk Agreements, as endorsed by the Security Council in resolution 2202 (2015).

"The secretary-general considers the decision of the Russian Federation to be a violation of the territorial integrity and sovereignty of Ukraine and inconsistent with the principles of the Charter of the United Nations," said the statement.

The United Nations, in line with the relevant General Assembly resolutions, remains "fully supportive of" the sovereignty, independence and territorial integrity of Ukraine, within its internationally recognized borders, according to the statement.

"The secretary-general urges all relevant actors to focus their efforts on ensuring an immediate cessation of hostilities, protection of civilians and civilian infrastructure, preventing any actions and statements that may further escalate the dangerous situation in and around Ukraine and prioritizing diplomacy to address all issues peacefully," it added.

At the day's press briefing, Dujarric said, "The secretary-general is greatly concerned with the latest reports of increased ceasefire violations, including the use of heavy weapons across the contact line in eastern Ukraine."

"We are particularly concerned regarding reports of civilian casualties, targeting of critical civilian infrastructure and evacuations," Dujarric said.

"We underline our call for an immediate cessation of hostilities, maximum restraint and for all parties to avoid any actions and statements that would escalate tensions further. All issues must be addressed through diplomacy," the spokesperson added.

Russian President Vladimir Putin announced on Monday that he had signed a decree recognizing "the Lugansk People's Republic (LPR)" and "the Donetsk People's Republic (DPR)" as independent and sovereign states.