A "Day of Silence" called by President Petro Poroshenko is being held in eastern Ukraine in an attempt to kick-start a much-violated ceasefire deal, reports GHN based on BBC.
However, new talks between pro-Russian rebels and the Ukrainian government appear uncertain.
The talks had been due to take place in Minsk, Belarus, on Tuesday.
Both sides signed a truce in Minsk in September, but almost 1,000 people have been killed in fighting since then, the UN says.
Mr Poroshenko said last week that troops would observe the Day of Silence on Tuesday to try to boost the peace deal.
The Ukrainian army would stop shelling and would possibly withdraw heavy weapons if it was clear that militants did the same, Mr Poroshenko said.
Some pro-Russian rebels reportedly welcomed the pledge, but it is not known if all groups had agreed to the proposal.
Since the conflict began in April, more than 4,300 people have died with almost one million displaced, the UN says.
Authorities in Minsk said they had not received any confirmation that either the Ukrainian government or rebel representatives would attend new peace talks, which were planned to begin on Tuesday.
Russian media reports say that the talks may now begin on Friday instead, but this has not been confirmed.
The previous Minsk agreement, brokered in September, projected a 30km (18 mile) military buffer zone in the east and limited self-rule for the separatists.
However, the rebel-held Luhansk and Donetsk regions then held leadership elections on 2 November that Ukraine and the West refused to recognise.