(QHA) -

Ukrainian President Petro Poroshenko has warned he may scrap a cease-fire after pro-Russian separatists in the east had violated a ceasefire with overnight attacks that killed one government soldier.

Rebels and Ukrainian forces have both vowed to observe a week-long ceasefire until June 27, but the government has reported rebels shooting at military checkpoints.

Poroshenko's statement on June 24 came after nine Ukrainian servicemen died when an Mi-8 military helicopter was hit by a rocket and crashed near the eastern city of Slovyansk.

That incident comes amid attacks by rebels on the Donetsk airport and checkpoints that led to several injuries and one death, despite separatist leaders agreeing on June 23 to Poroshenko's unilaterally-declared cease-fire.

As we earlier reported, Poroshenko declared a one-week cease-fire on June 20 as part of a peace plan to end the fighting which has killed hundreds.

He said insurgents have fired on Ukrainian positions 35 times since then.