Rebels in Ukraine agree to temporary ceasefire, Obama warns Russia

Ukraine's pro-Russian insurgents have agreed to a temporary ceasefire and talks with the new Western-backed president, as U.S. President Barack Obama warned Russia it risks fresh sanctions over its support for the separatists.

The surprise ceasefire announcement from the head of the self-proclaimed Donetsk People's Republic came a day after Russian President Vladimir Putin publicly threw his weight behind Kiev's peace overtures and urged the separatists to halt fire.

Ukraine's security services confirmed on June 23 evening that militia strikes in the two heavily-Russified industrial regions that have been at the heart of the insurgency came to an abrupt halt in the late afternoon.

The self-proclaimed prime minister of Donetsk said his side's ceasefire would match the one earlier ordered by President Petro Poroshenko and last until the end of the week.

"In response to the ceasefire declared by Kiev, we pledge to also halt fire on our part. This ceasefire will last until June 27," Oleksandr Borodai told Russia's ITAR-TASS news agency in Donetsk. "We hope that during the period in which both sides halt fire, we will be able to agree and begin consultations about holding negotiations about a peaceful settlement to the conflict," he told Russian state television in separate comments.

The White House said Obama told Russian President Vladimir Putin by phone on Monday that Russia would face new sanctions if it fails to stop the flow of weapons into Ukraine.

White House spokesman Josh Earnest said Obama used the call to drive home consistent US and Western warnings on Ukraine -- that Russia must stop supporting separatists in the east of the country and halt the flow of weapons across the border.

"Though we believe...