ROZDOLNE, Ukraine - Ukraine appealed for NATO's help on Wednesday after reporting that a huge convoy of tanks and weaponry from Russia was moving through the southeast of the country.
Kiev's claims came just hours after the first meeting in three months between President Petro Poroshenko and Russian counterpart Vladimir Putin failed to achieve any concrete breakthrough despite talk of a peace roadmap.
The military said a convoy of up to 100 tanks, armoured vehicles and rocket launchers was seen travelling towards Telmanove, a town about 80 kilometres (50 miles) south of the main rebel-held city of Donetsk and 20 kilometres from the Russian border.
Moscow was forced to admit Tuesday that a number of its troops captured by Ukrainian forces had crossed the border "by accident" but continues to deny arming the pro-Kremlin separatists who have been fighting Kiev's rule for four months in an increasingly bloody conflict.
Ukraine has accused its former masters in Moscow of sending in weapons to try to open another front in areas south of Donetsk after Kiev government forces made major advances against the rebels.
Call for 'decisive actions'
Poroshenko and Putin held marathon talks in the Belarus capital Minsk on Tuesday, alongside top EU officials, to try to find ways to end fighting that has now claimed over 2,200 lives in Ukraine's eastern industrial heartland.
Poroshenko said all sides had "without exception" agreed to his peace plan, but demanded "decisive actions which can help bring peace to Ukraine". He said he and Putin discussed the "necessity of closing Ukraine's borders" to prevent the movement of "equipment, mercenaries, and ammunition".
But Putin again insisted Russia had no role in the conflict, despite accusations by Kiev and the West that it is acting to further destabilise its western neighbour after the annexation of Crimea in March.
"We cannot discuss any ceasefire conditions," he said. "It's not our business, it's Ukraine's internal business." Putin also sought to play down the capture of 10 Russian paratroopers about 20 kilometres from the border after Russian military sources said they had crossed the border by accident.