KYIV/MOSCOW, MARCH 1

Moscow faced increasing isolation on Tuesday as President Vladimir Putin showed no sign of stopping an invasion of Ukraine, where fierce fighting and Russian bombardment have killed dozens and sparked a refugee crisis.

Russia's invasion, launched last week, has failed to achieve the decisive early gains that Putin would have hoped for. Ceasefire talks held Monday failed to reach a breakthrough and negotiators have not said when a new round would take place.

The United States and its allies have sought to punish Russia economically for staging the biggest assault on a European state since World War Two. They have imposed sanctions on Russia's top businesses, oligarchs and officials, including Putin himself.

But Washington has ruled out sending troops to fight Russia or enforcing a no-fly zone, fearing an escalation between the world's top two nuclear powers. Read full story It and its allies have instead promised military aid to Kyiv, as President Volodymyr Zelenskiy warns the capital is under constant threat.

"For the enemy, Kyiv is the key target," Zelenskiy said in a video message late on Monday. "We did not let them break the defence of the capital, and they send saboteurs to us ... We will neutralise them all."

Zelenskiy said that Russia, which calls its actions in Ukraine a "special operation", was targeting a thermal power plant that provides electricity to Kyiv, a city of 3 million people.

Russia says its actions are not designed to occupy territory but to destroy its southern neighbour's military capabilities and capture what it regards as dangerous nationalists.

Fighting has raged around the port of Mariupol and in the eastern city of Kharkiv, where Ukrainian officials said Russian artillery attacks had killed dozens of civilians, including children. It was not possible to verify those figures. Read full story

Staging a push for the capital, Russia has massed a convoy of armoured vehicles, tanks and other military equipment that stretches about 40 miles (64 km), the U.S. satellite company Maxar said.

Washington offered more support for Ukraine in the form of sanctions and weapons, Ukrainian Foreign minister Dmytro Kuleba said on Tuesday following a call with U.S. Secretary of State Antony Blinken.

"Ukraine craves for peace, but as long as we are under Russia's assault we need more sanctions and weapons. Secretary assured me of both," Kuleba wrote on Twitter.

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More than half a million people have fled Ukraine to neighbouring countries, according to the United Nations refugee agency, setting off a refugee crisis as thousands await passage at European border crossings.

At least 102 civilians in Ukraine have been killed since the invasion started Thursday, but the real figure could be much higher, the U.N.'s human rights chief said. Read full story

While Western-led sanctions have so far failed to convince Moscow to reverse course, a stream of companies pulling out of Russia is expected to grow on Tuesday and deal further blows to the country's economy.

Shell SHEL.L, BP BP.L and Norway's Equinor EQNR.OL all said they would exit positions in energy-rich Russia, putting pressure on other Western companies with stakes in Russian oil and gas projects, such as ExxonMobil XOM.N and TotalEnergies TTEF.PA.

Leading banks, airlines, and auto makers have cut shipments, ended partnerships and called Russia's actions unacceptable, with more considering similar actions. Read full story

The United States imposed new sanctions on Russia's central bank and other sources of wealth on Monday, triggering a plunge in the value of the rouble, and over the weekend some Russian banks were barred from the SWIFT international payments system. Read full story

Moves to isolate Russia have extended to culture and sports, as well. FIFA and UEFA suspended Russia's national teams and clubs from international football on Monday as sporting bodies around the world moved to bar Russian athletes from competing. Read full story

Putin, who takes pride in athleticism and is passionate about martial arts, had his honorary black belt from World Taekwondo stripped from him over the invasion, the group said.

"World Taekwondo strongly condemns the brutal attacks on innocent lives in Ukraine," it said in a statement.