KIEV: Ukraine’s president rallied support on Thursday for his plan to end fighting in the country’s east in phone calls with the Russian and German leaders, even as he condemned what Ukrainian officials called an incursion of armoured vehicles from Russia.

The Ukrainian interior minister said three tanks crossed into Ukraine along with other armoured vehicles from Russia and were attacked by military forces fighting pro-Moscow separatists.

He did not directly accuse Moscow of sending the tanks, but said it showed Russia had failed to fulfill promises to tighten border controls. Russia has denied sending troops or weapons to Ukraine, describing Russian citizens who have joined the armed separatists as volunteers.

There was no independent confirmation that the tanks had come from Russia. In Washington, US State Department spokeswoman Jen Psaki said if the military incursion was confirmed, it would be a “serious and disturbing escalation of the crisis in eastern Ukraine.

“The reported incursion followed statements earlier on Thursday by Russia’s foreign minister that the separatists were ready for a cease-fire but that Kiev had to initiate the process. Late on Thursday, an explosion shook the center of the major eastern city of Donetsk, where the rebels have taken over a regional administration building. A reporter nearby heard the explosion and arrived to see a van in flames in front of the building.

He saw three injured people being taken away. The breakaway Donetsk People’s Republic said on its Twitter feed that the van was used by one of the group’s leaders, Denis Pushilin, but said he was not in the vehicle.

The same tweet said four people were injured and one was in grave condition. Ukrainian President Petro Poroshenko, who took office less than a week ago, told Russian President Vladimir Putin that it was “unacceptable” that tanks had crossed the border, according to his spokesman, Svyatoslav Tsegolko.

A Kremlin statement said Poroshenko told Putin about his plan for resolving the crisis in the east, but did not say whether they discussed the tanks.

Published in Dawn, June 13th, 2014