Here are the latest developments in the war in Ukraine.

As the war in Ukraine marked its 100th day, Africa was urgently seeking relief from the disruptions of critical supplies of grain and other staple foods. Some of the world’s poorest countries face alarming levels of hunger and starvation and the United Nations has warned that Russia’s naval blockade of Ukraine could lead to famines around the world.

President Macky Sall of Senegal, the African Union chairman, was meeting with President Vladimir V. Putin of Russia on Friday at the Black Sea resort of Sochi to urge the Russian leader to lift the blockade on urgently needed cereals and fertilizer from Ukraine. Millions of tons of grain remain stuck in Ukraine and Mr. Putin has suggested that it could be freed up for export if Western countries lift their sanctions on Russia.

Sanctions have also caused a drop in Russian oil exports, prompting a reordering of the world’s energy market. On Thursday, OPEC Plus, a group of oil-producing nations effectively led by Saudi Arabia, agreed to raise production levels more than planned in July and August. The agreement comes after months of lobbying by the White House, and days after the European Union agreed to ban most imports of Russian oil.

As sanctions tighten on Moscow, Russian troops are making slow but substantial gains in Ukraine. President Volodymyr Zelensky said on Thursday that Russian forces now controlled one-fifth of his country. Fighting continues, Mr. Zelensky said, along a roughly 620-mile-long front that stretches from the northeastern city of Kharkiv to the outskirts of Mykolaiv, near the Black Sea, in the south.

For now, Moscow’s main military target is Sievierodonetsk, the last major city in the eastern Luhansk region that is not in Russian hands. Russia controls about 70 percent of the city, although a regional official said on Thursday that Ukrainian troops had forced Russian soldiers back from several streets amid fierce urban combat.

In other developments:

• Ukrainian forces have retaken 20 small towns and villages in the south of the country, an official said on Thursday, as part of a counteroffensive at a time when Moscow is intensely focused on its offensive in the east.

• In his nightly address, Mr. Zelensky said that 50 foreign embassies had resumed “their full-fledged activities” in Kyiv.

• The U.S. government imposed sanctions on a yacht management company and its owners, describing them as part of a corrupt system that allows Russian elites and Mr. Putin to enrich themselves, the Treasury Department said on Thursday.