Bakhmut (Ukraine) (AFP) - Artillery exchanges pounded war-scarred cities in eastern Ukraine on Friday despite Russian leader Vladimir Putin unilaterally ordering his forces to pause attacks for 36 hours for the Orthodox Christmas.

The brief ceasefire declared by Putin earlier this week was supposed to begin at 0900 GMT Friday and would have been the first full pause since Moscow's invasion in February 2022.

But AFP journalists heard both outgoing and incoming shelling in the frontline city of Bakhmut in eastern Ukraine after the time when the Russian ceasefire was supposed to have begun.

Moscow's forces also struck Kramatorsk in the east, the Ukrainian presidential administration said, as well as the frontline town of Kurakhove where residential buildings and a medical facility were damaged.

Putin's order to stop fighting during the Orthodox Christmas came after Moscow suffered its worst reported loss of life yet, and was followed by a US announcement of more than $3 billion in military aid for Kyiv -- its largest single assistance package of the war.

Ceasefire 'not serious'

Kyrylo Tymoshenko from the Ukraine president's office earlier said that Moscow's forces had struck a fire station in southern city of Kherson in an attack that left several people dead or wounded.

"They talk about a ceasefire. This is who we are at war with," he said.

The head of Ukraine's Lugansk region meanwhile added that Russian forces had fired 14 times on Kyiv's position and attempted to storm a settlement held by Ukrainian forces.

Russia's defence ministry said however it was respecting its unilateral ceasefire and accused Ukraine's forces of continued shelling.

Both countries celebrate Orthodox Christmas and the Russian leader's order came following ceasefire calls from Turkish President Recep Tayyip Erdogan and Russia's spiritual leader Patriarch Kirill, a staunch Putin supporter.

Ukraine had already dismissed the halt -- due to last until the end of Saturday (2100 GMT) -- as a strategy by Russia to gain time to regroup its forces and bolster its defences following a series of battlefield reversals.

The US State Department said the Russian strikes prove the ceasefire was a "cynical" ploy, while the French foreign ministry described it as a "crude" attempt by Moscow to divert attention from its culpability for the war.

The EU's most senior diplomat said Friday the ceasefire was "not credible".

"The Kremlin totally lacks credibility and this declaration of a unilateral ceasefire is not credible," European Union foreign policy chief Josep Borrell said during a visit to Morocco.

Since the invasion began on February 24 last year, Russia has occupied parts of eastern and southern Ukraine, but Kyiv has reclaimed swathes of its territory and this week claimed a New Year's strike that killed scores of Moscow's troops.

In Bakhmut, located in the Donetsk region, dozens of civilians gathered at a building used as a base for disbursing humanitarian aid, where volunteers organised a Christmas Eve celebration less than an hour after the ceasefire was to go into effect, handing out mandarins, apples and cookies.

The streets of the largely bombed-out city were mostly empty save for military vehicles. Shelling was lighter on Friday than it had been in recent days.

Pavlo Diachenko, a police officer in Bakhmut, said he doubted the ceasefire would mean much to the city's civilians even if it had been respected.

"What can a church holiday mean for them? They are shelling every day and night and almost every day there are people killed," he said.

There was also widespread scepticism of the ceasefire in the streets of Kyiv.

"You can never trust them, never... Whatever they promise, they don't deliver," said Olena Fedorenko, a 46-year-old from the war-torn city of Mykolaiv in southern Ukraine.

$3 bn in aid

Far from the frontline, Moscow resident Tatyana Zakharova said she was not in a festive mood on the eve of Orthodox Christmas because her brother was fighting in Ukraine.

"Of course, we will go to church... we will pray first of all for my brother, our boys," the 35-year-old told AFP.

The United States on Friday announced a more than $3 billion aid package for Ukraine that includes 50 Bradleys and dozens of other armoured vehicles, as well as artillery pieces and ammunition.

It is "the largest security assistance package in total value that we have committed so far," US Deputy Assistant Secretary of Defence Laura Cooper told journalists.

Ukrainian President Volodymyr Zelensky hailed the new package as "timely and strong." It brings total US military assistance since Russia invaded in February 2022 to more than $24.2 billion.

Both Washington and Berlin had pledged to provide infantry fighting vehicles for Ukraine the previous day, with Germany saying Friday it would deliver about 40 Marder vehicles within weeks.