KYIV, Ukraine (AP) - Ukraine's leader petitioned for more powerful Western weapons as he prepared to meet with top U.S. officials in the war-torn country's capital Sunday and Russian forces concentrated their attacks on the east, including trying to dislodge the last Ukrainian troops holding out in the battered port city of Mariupol.

President Volodymyr Zelenskyy announced the planned visit by U.S. Secretary of State Antony Blinken and U.S. Defense Secretary Lloyd Austin during a lengthy Saturday night news conference held in a Kyiv subway station. The White House has not commented.

Zelenskyy said he was looking for the Americans to produce results, both in terms of arms and security guarantees. "You can’t come to us empty-handed today, and we are expecting not just presents or some kind of cakes, we are expecting specific things and specific weapons,'' he said.

The visit would be the first by senior U.S. officials since Russia invaded Ukraine 60 days ago. Blinken stepped briefly onto Ukrainian soil in March to meet with the country's foreign minister during a visit to Poland. Zelenskyy’s last face-to-face meeting with a U.S. leader was Feb. 19 in Munich with Vice President Kamala Harris.

The meeting was set to take place as Ukrainians and Russians observed Orthodox Easter, celebrating the resurrection of Jesus Christ and considered the most joyful holiday on the Christian calendar.

Speaking Sunday from the ancient St. Sophia Cathedral, Zelenskyy, who is Jewish, highlighted the allegorical significance of the occasion to a nation wracked by nearly two months of war.

“The great holiday today gives us great hope and unwavering faith that light will overcome darkness, good will overcome evil, life will overcome death, and therefore Ukraine will surely win!” he said.

Earlier, during his nightly address to the nation, Zelenskyy claimed that intercepted communications recorded Russian troops discussing “how they conceal the traces of their crimes” in Mariupol. The president also highlighted the death of a 3-month old girl in a Russian missile strike Saturday on the Black Sea port of Odesa.

Zelenskyy said that equipment from Western supporters had been a big help so far, but he also has stressed that Ukraine needs more heavy weapons, including long-range air defense systems, as well as warplanes to fend off the Russian attacks.

The Russian military reported that it hit 423 Ukrainian targets overnight, including fortified positions and troops concentrations, while Russian warplanes destroyed 26 Ukrainian military sites, including an explosives factory and several artillery depots.

Most of the fighting Sunday focused on the eastern Donbas region, where Ukrainian forces are concentrated and where Moscow-backed separatists controlled some territory before the war. Since failing to capture Kyiv, the Russians are aiming to gain full control over Ukraine’s eastern industrial heartland.

Russian forces launched fresh airstrikes on a Mariupol steel plant where an estimated 1,000 civilians are sheltering along with about 2,000 Ukrainian fighters. The Azovstal steel mill where the defenders are holed up is the last corner of resistance in the city, which the Russians have otherwise occupied.

Mykhailo Podolyak, a Ukrainian presidential adviser, called for a localized Easter truce. He urged Russia to allow civilians to leave the plant and suggested talks to negotiate an exit for the Ukrainian soldiers.

Podolyak tweeted that the Russian military was attacking the plant with heavy bombs and artillery while accumulating forces and equipment for a direct assault.

Mariupol has been the focus of fierce fighting since the start of the war due to its location on the Sea of Azov. Its capture would deprive Ukraine of a vital port, free up Russian troops to fight elsewhere, and allow Moscow to establish a land corridor to the Crimean Peninsula, which it seized from Ukraine in 2014.

More than 100,000 people - down from a prewar population of about 430,000 - are believed to remain in Mariupol with scant food, water or heat. Ukrainian authorities estimate that over 20,000 civilians have been killed.

Satellite images released this week showed what appeared to be mass graves dug in towns to the west and east of Mariupol.

Zelenskyy accused the Russians of committing war crimes by killing civilians, as well as of setting up “filtration camps” near Mariupol for people caught trying to leave the city. From there, he said, Ukrainians are sent to areas under Russian occupation or to Russia itself, often as far as Siberia or the Far East. Many of them, he said, are children.

The claims could not be independently verified.

In attacks on the eve of Orthodox Easter, Russian forces pounded cities and towns in southern and eastern Ukraine. The 3-month-old baby was among eight people killed when Russia fired cruise missiles at Odesa, Ukrainian officials said.

Ukrainian news agency UNIAN, citing social media posts, reported that the infant's mother, Valeria Glodan, and grandmother also died when a missile hit a residential area. Zelenskyy promised to find and punish those responsible for the strike.

“The war started when this baby was one month old,'' he said. Can you imagine what is happening? “They are filthy scum, there are no other words for it.”"

For the Donbas offensive, Russia has reassembled troops who fought around Kyiv and in northern Ukraine earlier. The British Ministry of Defense said Sunday that Ukrainian forces had repelled numerous assaults in the past week and "inflicted significant cost on Russian forces.”

“Poor Russian morale and limited time to reconstitute, re-equip and reorganize forces from prior offensives are likely hindering Russian combat effectiveness,” the ministry said in an intelligence update.

The Ukrainian military said Saturday it destroyed a Russian command post in Kherson, a southern city that fell to Russian forces early in the war.

The command post was hit on Friday, killing two generals and critically wounding another, the Ukrainian military intelligence agency said in a statement. The Russian military did not comment on the claim, which could not be confirmed.

If true, at least nine Russian generals have been killed since the start of the invasion, according to Ukrainian reports.