WASHINGTON, Oct. 8 - The United States warned on Thursday that it would maintain economic sanctions imposed on Russia over its intervention in Ukraine until the terms of a peace plan are fully implemented, AFP reported.

Ukraine's President Petro Poroshenko had announced on Wednesday that a "real truce" had begun in the east of his country, where Kiev's forces had been battling pro-Russian separatist rebels for more than a year.

But Victoria Nuland, US Assistant Secretary of State for European and Eurasian Affairs, told US lawmakers that Washington's measures to punish Moscow for its actions against its neighbor would remain in place for now.

Nuland told the Senate Foreign Relations Committee that Moscow must now implement the terms of the Minsk peace agreement of February 2015, which lays out a plan to demilitarize the conflict and seek political compromise.

And she warned that a second set of sanctions imposed on Russia after it formally annexed the Ukrainian region of Crimea would remain in place until President Vladimir Putin agrees to withdraw his forces.

"We will judge Russia and the separatists by their actions, not their words," she said.

"We will work with the EU to keep sanctions in place until the Minsk agreements are fully implemented.

"And of course, Crimea sanctions remain in place so long as the Kremlin imposes its will on that piece of Ukrainian land," she said.

The Minsk agreement, signed between Kiev and Moscow and brokered by Berlin and Paris, foresees the withdrawal of heavy weapons from the battlefield and a vote held in the separatist region under international auspices.

"If these commitments are kept -- if weapons are pulled back and stored, if the OSCE gets in, and legal, monitored elections are negotiated and held, Ukraine will once again have unfettered access to its own people and its territory in the East," Nuland said.

"That's what Minsk promises: peace, weapons withdrawal, political normalization, then a return of the border." (afp/ez)