Paris, Apr 19 (IANS): French President Emmanuel Macron said it was "unacceptable" that Russian troops are amassing along Ukraine's eastern border and called for a tough stance against the threat of fresh military aggression from Moscow.

"The situation today and the level of tension at the border is absolutely counterproductive and unacceptable," Macron said in an interview that aired on Sunday, DPA news agency reported.

While he was in favour of accelerating diplomatic efforts to ease the tensions, Macron said the discussions with Moscow needed to be "clear and tough".

"I think we have to define clear red lines with Russia," Macron told US television channel CBS.

"This is the only way to be credible. I think that sanctions are not sufficient in itself, in themselves, but sanctions are part of the package," he said.

Macron has put himself at the forefront of the diplomatic push to ease the latest flare up in Ukraine's conflict.

He held discussions with German Chancellor Angela Merkel and Ukrainian President Volodymyr Zelensky on Friday. The three demanded Russia pull back troops and urged that a shaky ceasefire in eastern Ukraine be recommitted to.

New consultation-level talks with Franco-German mediation are planned for Monday, according to Zelensky.

Anxiety is growing about the conflict that erupted between the Ukrainian military and Russian-backed separatist rebels in 2014, the same year that Russian forces annexed the Crimean peninsula further south.

Parts of Ukraine's eastern Donetsk and Luhansk regions along the Russian border have been controlled by rebels supported by Moscow for nearly seven years.