Seven people were reportedly killed in the latest clashes, which occurred in the coastal city of Mariupol in southeastern Ukraine overnight.

The fighting, which included an intense artillery duel, took place along the front line between Ukrainian troops and pro-Russian separatists.

Local residents have described the battle as the heaviest in more than three months, Radio Free Europe informs.

According to reports, houses were destroyed in the village of Sartana and an oil depot was also damaged.

Regional police informed that two civilians – a man and a woman were killed in the shelling by separatists in Sartana.

At the same time, separatists claimed that at least three people were killed in a shelling by government troops in the city of Horlivka.

There were also reports of shelling by Ukrainian forces in the separatist-controlled city of Donetsk on Sunday.

Russian Foreign Minister Sergey Lavrov said on Monday that the latest developments in eastern Ukraine hinted of a possible preparation by Kiev to renew large-scale fighting.

The latest surge in violence comes after a week of intensifying clashes near Mariupol with both sides hurling mutual accusations at each other.

German Foreign Minister Frank-Walter Steinmeier warned on Sunday that the situation in eastern Ukraine is explosive and urgent talks were necessary to prevent a new escalation of violence.

Steinmeier has called for holding an immediate meeting between representatives of the Ukrainian authorities, the separatists and the OSCE.