Moscow- Shelling suddenly stopped at midnight in the eastern Ukrainian city of Donetsk after President Petro Poroshenko gave the order to government forces to halt firing in line with a ceasefire agreement reached last Thursday.

Poroshenko, wearing the uniform of the armed forces supreme commander, said in a televised address in the capital Kiev that there was still "alarm" over the situation around Debaltseve, a key transport hub, where government forces are hard pressed by encircling Russian-backed separatists.

And he warned that Ukraine, if it was slapped once, would not offer the other cheek.

But, seated alongside armed forces chief of staff Viktor Muzhenko, he added: "I very much hope that the last chance to begin the long and difficult peaceful process for a political settlement will not be wasted."

"As a first step I now give the order to the armed forces ofUkraine ... to cease fire at 00:00 hours on February 15," he said.

Military spokesman Vladyslav Selezynov said the Ukrainian armed forces immediately fulfilled the order and the big guns fell silent in Donetsk and some other parts of the separatist-leaning east.

The ceasefire, negotiated in four-power talks in Belarus last Thursday, foresees creation of a neutral "buffer zone" and withdrawal of heavy weapons responsible for many of the 5,000 deaths in a conflict that has caused the worst crisis in Russia-West relations since the Cold War a generation ago.

Earlier in the run-up to midnight, heavy artillery and rocket fire roughly every five seconds had reverberated across Donetsk, the main regional city in the east which is under the control of the pro-Russian secessionists.

In Artemivsk, a town in government-controlled territory north of Debaltseve which has been hit twice in two days by rocket attacks, there was also silence at midnight.

A member of a Ukrainian pro-government unit near the eastern town of Horlivka, who only gave his nickname of Turnir, said on television channel 112: "It's quiet. It's been quiet for half an hour. But we are waiting. We don't believe them. For the past three days they have been banging us hard."

Debaltseve, a strategic rail junction that lies in a pocket between the two main rebel-held regions, has been the focus of some of the fiercest recent fighting.