Following fresh shelling near Donetsk airport in eastern Ukraine Sunday, a ceasefire agreement signed by the government and the separatists might collapse, observers said.
The truce and 12-point peace roadmap was signed at talks involving Ukraine, Russia, the rebels and the Organisation for Security and Co-operation (OSCE) in Europe Friday, BBC reported.
The truce was held for much of Saturday but overnight shelling in Mariupol was followed by the explosions near Donetsk airport, officials said.
According to eyewitnesses, pro-Russian rebels shelled and destroyed an important government check point in Mariupol.
Before the ceasefire was agreed Friday, the separatists were advancing towards Donetsk airport and Mariupol.
According to UN reports, the turmoil in Ukraine has left some 2,600 people dead since it started in April.