WRAPUP 19-Western allies to expel key Russian banks from global system; Ukraine vows to fight on

* Ukraine's president says repelling attacks

* Long queues at ATMs and gas stations

* Biden approves $350 million worth of military aid

* Western allies to kick major Russia banks off SWIFT system

* Russia says its forces advancing 'on all sides'

* Kyiv mayor imposes curfew against saboteurs

By Maria Tsvetkova and Aleksandar Vasovic

KYIV, Feb 26 (Reuters) - Western allies announced sweeping new sanctions against Moscow on Saturday, including kicking key Russian banks off the main global payments system, as a defiant President Volodymyr Zelenskiy said Ukrainian forces were repelling Russian troops advancing on Kyiv.

Seeking to ratchet up economic punishment for Russian President Vladimir Putin over his invasion of Ukraine, the United States and its European partners also said they would impose restrictions on Russia's central bank to limit its ability to support the rouble and finance his war effort.

The announcement came as fighting continued across Ukraine. Reuters witnesses in Kyiv reported occasional blasts and gunfire in the city on Saturday evening, but it was not clear exactly where it was coming from. The capital and other cities have been pounded by Russian artillery and cruise missiles.

Putin launched what he called a special military operation on Thursday, ignoring weeks of Western warnings and saying the "neo-Nazis" ruling Ukraine threatened Russia's security - a charge Kyiv and Western governments say is baseless propaganda.

Russia's assault is the biggest on a European state since World War Two and threatens to upend the continent's post-Cold War order.

A U.S. defence official said Ukraine's forces were putting up "very determined resistance" to the three-pronged Russian advance that has sent hundreds of thousands of Ukrainians fleeing westwards, clogging major highways and railway lines.

"As Russian forces unleash their assault on Kyiv and other Ukrainian cities, we are resolved to continue imposing costs on Russia that will further isolate Russia from the international financial system and our economies," the Western allies said as they escalated their punitive response.

"We will implement these measures within the coming days," according to a joint statement https://www.whitehouse.gov/briefing-room/statements-releases/2022/02/26/joint-statement-on-further-restrictive-economic-measures from the United States, France, Germany, Canada, Italy, Britain and the European Commission.

After initially shying away from such a move largely because of concern about the impact on their own economies, the allies said they committed to "ensuring that selected Russian banks are removed from the SWIFT messaging system." They did not name the banks that would be expelled but an EU diplomat said some 70% of the Russian banking market would be affected.