More than 1.36 million people have been forced to flee Ukraine since Russian forces invaded on Feb. 24, according to the latest figures from the United Nations High Commissioner for Refugees (UNHCR).

More than 756,000 of the refugees from Ukraine are in neighboring Poland, UNHCR figures show.

Russia's flagship airline Aeroflot announced Saturday that it will temporarily suspend all international flights from March 8.

In a statement on its website, the airline cited "the occurrence of additional circumstances that impede the operation of flights."

"The cancellation also applies to international destinations in the schedule of Rossiya and Aurora airlines," Aeroflot said.

Russian forces continued to shell Ukraine's strategic port city of Mariupol on Saturday despite agreeing to a temporary cease-fire to allow civilians to evacuate, according to the regional governor.

"Due to the fact that the Russians do not observe the regime of silence and continue shelling of Mariupol and its environs, for security reasons, the evacuation of the population has been postponed," Donetsk Oblast Gov. Pavlo Kyrylenko said in a statement posted on social media. "We ask people to leave the gathering places and go to the shelters. Additional information about the evacuation will be posted soon. Police officers will also use loudspeakers to inform the city's residents."

The Associated Press reported that Kyrylo Tymoshenko, deputy head of the Ukrainian president's office, confirmed that the evacuation effort in Mariupol was stopped because the city remained under fire on Saturday.

"The Russian side is not holding to the ceasefire and has continued firing on Mariupol itself and on its surrounding area," Tymoshenko said, according to AP. "Talks with the Russian Federation are ongoing regarding setting up a cease-fire and ensuring a safe humanitarian corridor."

Earlier Saturday, the Russian Ministry of Defense announced that it has agreed with Ukrainian forces to open humanitarian corridors in Mariupol, a strategic port in the southeast, and in the eastern city of Volnovakha between 10 a.m. and 5 p.m. Moscow time. The deal was reached during the second round of talks between Russian and Ukrainian delegations earlier this week.

Mariupol has been under ferocious, indiscriminate bombardment with heavy artillery and missile strikes for days, causing the city to sometimes lose power and water. Local officials have described bodies strewn across the streets because authorities are unable to collect them.

-ABC News' Patrick Reevell

Russia announced Saturday a temporary cease-fire in two besieged cities of Ukraine to allow civilians to evacuate.

The Russian Ministry of Defense said in a statement carried by state news agencies that it has agreed with Ukrainian forces to open humanitarian corridors in the strategic port of Mariupol and the eastern town of Volnovakha beginning at 10 a.m. Moscow time.

"Starting at 10 a.m. Moscow time today, on March 5, the Russian side declares a ceasefire and opens humanitarian passages for civilians to leave Mariupol and Volnovakha," the ministry said. "Humanitarian passages and exit routes have been coordinated with the Ukrainian side."

There was no immediate confirmation from Ukraine, and it was unclear how long the evacuation routes would remain open.

-ABC News' Anastasia Bagaeva

Russia's representative to the United Nations on Friday reiterated the Kremlin's claim that Ukrainian forces were responsible for the attack on the Zaporizhzhia nuclear power plant.

The representative said Russian forces came under small arms fire by a "Ukrainian sabotage group" that was stationed in a training complex building on site.

The representative claimed that Russian troops returned fire, but that as they departed, Ukrainians set the building on fire.

The Russian representative claimed Ukrainian "radicals" are under the West's "close guardianship and protection," giving them "carte blanche," and allowing them to act like "ISIS terrorists" by "hiding behind civilians and placing heavy weaponry and multiple rocket launchers in residential areas."

Ukraine, the U.S. and its allies have denied these claims.

The UN relief chief also fact-checked the Russian delegate on Monday, saying Russia's claim about Ukraine placing weapons in civilian areas was false.

- ABC News' Conor Finnegan