Ukraine is hardening its position in negotiations to end the conflict in the country's east, saying it must regain control of its entire border with Russia before elections can be held in the regions controlled by Russia-backed rebels.

The agreement worked out last year by the leaders of Ukraine, Russia, France and Germany says Ukraine would regain control of the border the day after such elections were held.

But after a meeting Wednesday with the so-called Contact Group trying to implement the pact, Ukraine's representative — former president Leonid Kuchma — said elections were impossible without border control, his spokeswoman Darka Olifer said in a statement on Facebook.