Fighting rumbled on in east Ukraine Thursday between government troops and pro-Russian rebels despite a fresh push for ceasefire talks from international envoys.
Ukraine's border service said that nine guards were wounded when rebels shelled the Dolzhansky border post with Russia, a strategic crossing that Kiev won back days earlier in a step hailed as the "first victory" since the renewal of its military offensive.
Elsewhere, the defence ministry said in a statement that its forces had destroyed five trucks carrying "terrorists".
The statement said that rebels had launched 16 attacks on government checkpoints during the past 24 hours.
Ukraine's President Petro Poroshenko this week ripped up a 10-day truce, which Kiev says the insurgents broke over 100 times at the cost of 30 lives. The military then announced a "massive" anti-rebel operation in the eastern rustbelt.
The latest clashes came as French President Francois Hollande and German Chancellor Angela asked Russian President Vladimir Putin to help organise a Contact Group meeting before the weekend in order to define the conditions for a ceasefire.
They urged him to persuade the pro-Moscow separatists to negotiate.
Russia and Ukraine's foreign ministers agreeing in Berlin on Wednesday that the new talks for a fresh ceasefire should be held this week.
German Foreign Minister Frank-Walter Steinmeier hastily convened a crisis meeting, also involving his French counterpart Laurent Fabius, warning that unless truce talks resume, the country could face "an explosion of violence".
Ukrainian troops backed by tanks and bomber jets have stepped up the fighting since the end of the ceasefire that failed to stem Europe's deadliest fighting in nearly two decades that has claimed over 450 lives in 11 weeks.
Both Kiev and the separatists refuse to negotiate directly with each other but the four envoys called for fresh talks by Saturday involving Moscow, a Kiev proxy, the rebels and the Organisation for Security and Cooperation in Europe (OSCE).
Rebels said Thursday they were prepared to take part in indirect talks only if Moscow and international observers were involved.
"If Russia and the OSCE make a proposal to us then we are willing to participate in consultations," Andriy Purgin, deputy prime minister of the self-proclaimed Donetsk People's Republic, told AFP.
Russia's Interfax news agency cited an unnamed source close to the talks as saying that a fresh meeting involving separatist leaders and former Ukraine president Leonid Kuchma as Kiev's representative could happen late Friday.
Military reshuffle
For its part Kiev has called for OSCE observers to monitor its porous border with Russia, across which it accuses Moscow of sending fighters and weapons. It said it will not endorse a ceasefire until it has full control over the frontier.
Highlighting its shaky control, Ukraine's border service on Thursday accused Russian military helicopters of breaching its borders by crossing briefly into Ukrainian airspace at several points along the frontier.
In a sign that the offensive against the rebels could be set to intensify, Western-backed Poroshenko on Thursday reshuffled his top military leaders, naming a new defence minister and army chief.
"I am sure that Ukraine will win and believe me that there will be a victory parade," Valeriy Geletey, a former police commander, told parliament after his confirmation as minister.
On the ground in the rebel-held territories the security situation continued to deteriorate even away from the frontline.
Standoff continues
An AFP journalist on Thursday saw the bodies of three traffic policemen who had been shot dead close to the main separatist-controlled city of Donetsk.
Despite the public consensus for the need for talks at the meeting in Berlin, the West and Russia remain at loggerheads over the conflict in Ukraine and the threat of fresh sanctions against Moscow remains on the table.
Putin has charged Poroshenko bears full responsibility for the latest deaths.
But Washington earlier voiced strong support for Poroshenko, with a State Department spokeswoman saying that "Ukrainian forces have a responsibility to defend their territory and their people" in the face of "aggression by Russian-backed separatists".
NATO chief Anders Fogh Rasmussen said Wednesday that "Russia's actions threaten the peace and security we have built after the fall of the Berlin Wall".
