INTERNATIONAL: Air raid sirens sounded across Ukraine before dawn on Tuesday as Ukrainian and Russian negotiators prepared to meet in Turkey for face-to-face talks, with Kyiv seeking a ceasefire without compromising on territory or sovereignty.

Ukraine and the United States hold little hope of a breakthrough at the meeting, the first direct talks between the two sides in more than two weeks, even though Russia's invasion appeared to have stalled on several fronts.

More than a month into the war, the biggest attack on a European nation since World War Two, more than 3.8 million people have fled abroad, thousands have been killed and injured, and Russia's economy has been pummeled by sanctions.

In the besieged southern port city of Mariupol, nearly 5,000 people have been killed, including about 210 children, according to figures from the mayor. Reuters was unable to immediately verify the numbers.

Survivors have told harrowing tales of people dying from lack of medical treatment, bodies being buried wherever space could be found, and women giving birth in basements.

Ukrainian Foreign Minister Dmytro Kuleba said of the talks in Turkey: "We are not trading people, land, or sovereignty."

"The minimum program will be humanitarian questions, and the maximum program is reaching an agreement on a ceasefire," he said on national television.

A senior U.S. State Department official said Russian President Vladimir Putin did not appear ready to make compromises to end the war. read more

Ukrainian interior ministry adviser Vadym Denysenko said that he doubted there would be any breakthrough.

Kremlin spokesperson Dmitry Peskov said talks so far had not yielded any substantial progress but it was important they continued in person. He declined to give more information.

In besieged Ukrainian cities where conditions are desperate, the threat of Russian attacks has blocked exit routes for civilians, two Ukrainian officials said.

In Mariupol, the mayor said about 160,000 people were trapped.

"There is no food for the children, especially the infants. They delivered babies in basements because women had nowhere to go to give birth, all the maternity hospitals were destroyed," a grocery worker from Mariupol who gave her name only as Nataliia told Reuters after reaching nearby Zaporizhzhia.

As the humanitarian toll continues to rise, the United Nations said it had been able to bring food and medical supplies into Kharkiv, Ukraine's second-biggest city and one of its hardest hits.