Ukraine's parliament commissioner for human rights, Dmytro Lubinets, confirmed in a social media post that the ceasefire had begun.
A truce has begun in the Russian-occupied Ukrainian city of Oleshky, a week after it was announced by US First Lady Melania Trump.
The ceasefire is meant to allow aid deliveries and the evacuation of civilians.
Russia's defence ministry said on Telegram it had stopped firing toward the Ukrainian city of Kherson - across the river from Oleshky - at 04:00 Moscow time (01:00 GMT) in preparation for the humanitarian operation.
Oleshky is on the south bank of the river Dnipro, which forms the front line in the Kherson region. The remaining residents have been desperately short of food and other essential supplies.
"As head of the Ukrainian negotiating team, I confirm that the Ukrainian side is honouring its commitments," he wrote on Facebook.
Oleshky was seized by Russia during the first days of its full-scale invasion in February 2022.
Source: The Star