On Thursday, the Kremlin ordered Russian troops to cease fire due to the Russian Orthodox Christmas.
The truce was to last 36 hours, from noon Friday to midnight Sunday night.
Putin also called for a ceasefire in Ukraine.
But it didn't take long for reports that the ceasefire had ended.
- Shortly after the cease-fire began, aircraft alarms were heard all over Ukraine, says Sveriges Radio's foreign correspondent Lubna El-Shanti to Ekot.
According to the AFP news agency, firefights have taken place on the front line in the city of Bakhmut in eastern Ukraine.
According to the news agency's journalists on site, both incoming and outgoing fire was heard.
"Which cease-fire?"
According to a spokesperson for Zelensky's administration, Russian forces also attacked the city of Kramatorsk in eastern Ukraine after the ceasefire was issued.
- Which ceasefire?
We have learned not to trust them, says a Ukrainian soldier.
The countries blame each other
The Russian Ministry of Defense maintains that the country respects the ceasefire.
At the same time, they accuse Ukraine of artillery fire against people and Russian positions, writes AFP.
Hear Ukrainian soldiers share their thoughts on the one-sided ceasefire in the clip above.