April 28 (UPI) -- United Nations Secretary-General Antonio Guterres is to meet Ukrainian President Volodymyr Zelensky and other officials on Thursday in Kyiv as he seeks to improve the humanitarian situation in the war-torn country. The U.N. chief landed in Kyiv late Wednesday after meetings with Russian President Vladimir Putin in Moscow.

"We will continue our work to expand humanitarian support & secure the evacuation of civilians from conflict zones," Guterres tweeted on landing in Ukraine. "The sooner this war ends, the better -- for the sake of Ukraine, Russia and the world."

Guterres had embarked upon the his Europe trip Monday, which began with a stop over in Turkey for talks with its president, Recep Tayyip Erdogan, before heading to Moscow for talks with Putin, who agreed "in principle" to allow the U.N. and the International Committee of the Red Cross to be involved in evacuating civilians from an iron and steel plant in the besieged southeastern Ukrainian city of Mariupol. 

Russian attacks have targeted the Azovstal plant where resistant fighters and civilians have sought refuge. The ICRC over the weekend called for immediate and unimpeded humanitarian access to allow thousands of civilians and hundreds of wounded to evacuate from the city and the plant. 

Fahan Haq, deputy spokesman for Guterres, told reporters during a press briefing Wednesday that the U.N. held follow-up conversations about those evacuations efforts with officials in Moscow and Kyiv, specifically about developing an operational framework for that effort.

"Speed is of the essence," he said, adding they have put people on the ground to in preparation.

"Ultimately, what we want is to make sure a cease-fire would be respected that would allow us to move people safely," he said.

The evacuations, however, depend on the outcome of discussions with both parties, he added.

Guterres' trip to Ukraine comes as the country's defense minister, Oleksiy Reznikov, warned of "extremely difficult weeks ahead."

Ahead of the trip Haq had told reporters that Guterres believed that there was a "real opportunity" to achieve either a cease-fire or concrete improvements in the humanitarian situation in Ukraine.

Russia invaded Ukraine Feb. 24, resulting in nearly 2,800 civilians killed and more than 5.3 million forced to flee the country, according to U.N. data. UPI