Six soldiers were killed and a journalist injured by a mine in separatist-held eastern Ukraine Tuesday as a flare-up of fighting undermined a shaky two-month cease-fire. The situation in the conflict zone "remains unstable", with "armed provocations by the enemy continuing on almost all sides," military spokesman Andriy Lysenko said.
Lysenko said six soldiers had been killed and 12 injured in a surge of fighting in the previous 24 hours.
The deaths, the highest toll in the last 10 days, come as the foreign ministers of Ukraine, Russia, Germany and France expressed "grave concern" over surging violations of the February cease-fire.
The top diplomats from the four countries held talks in Berlin overnight to evaluate the status of the truce deal aimed at ending a year of fighting that has killed more than 6,000 people.
Talks on the situation in Ukraine are expected to continue at a meeting of G7 foreign ministers in the northern German city of Luebeck on Tuesday and Wednesday, attended by US Secretary of State John Kerry.
Lysenko said separatist insurgents used 120mm mortars and 122mm cannons against the army despite an agreement under the cease-fire deal to withdraw all such weaponry from the frontline.
The heaviest fighting took place around the airport of the rebel bastion of Donetsk, a city once home to a million people in the industrial east.
Another hotspot was Shyrokyne, on the outskirts of the strategic port city of Mariupol, the last major city still in government hands in the east.
Russian TV network Zvezda, which is controlled by the defence ministry, said one of its journalists was badly injured there after stepping on a landmine. An AFP journalist at the scene said the reporter was with insurgents when the incident occurred.
The accident occurred as monitors from the Organisation for Security and Co-operation in Europe (OSCE) visited the village.
The deputy head of the OSCE monitoring mission Alexander Hug said medics were able to stabilise him before he was evacuated for treatment.
He also urged both sides to cease fire in Shyrokyne and to provide OSCE monitors with unhindered access at all times.
"I once again call for all the sides to pull away arms from Shyrokyne and underline the importance that all sides grant ... access to the mission.Yesterday our mission could only move three hundred meters (yards) into the village not any further," he told a news briefing.
In Berlin, German Foreign Minister Frank-Walter Steinmeier said the five-hour talks had been "very long, very intensive and at times very contentious" given the tense situation on the ground.
"We must ensure that the cease-fire is respected a lot more comprehensively than it was in recent days," he told reporters. After weeks in which the cease-fire agreed in the Belarussian capital Minsk appeared to be largely holding despite isolated skirmishes, clashes now seem to be mounting in flashpoint areas.
Ukrainian army spokesman Oleksandr Motuzianyk said Monday one soldier had been killed and six hurt in 24 hours. Separatist officials said four civilians had been injured in the conflict zone.
European OSCE monitors reported "renewed intensive fighting" Sunday around the rebel stronghold of Donetsk, with more than 1,166 explosions in under six hours, mainly from artillery and mortar fire.