Ukraine's government and pro-Russian rebels have signed a memorandum aimed at halting all fighting in the east of the country.
The plan creates a buffer zone in areas where conflict has been continuing.
It demands that all troops and foreign mercenaries be pulled back.
Earlier, Russia delivered a third shipment of aid to rebel-controlled Ukraine.
It sent trucks carrying water and food across the border, a spokesman for Russia's emergencies ministry said.
He said the convoy - the first aid shipment to the flash point city of Donetsk.
It had been sent across the state border unaccompanied by any international or Ukrainian government monitors.
Russia has previously sent two aid convoys to the rebel-held Lugansk region without the final agreement of Ukraine and Red Cross monitors, sparking outrage in Kiev.
Russian state channel Rossiya 24 said the convoy of 200 vehicles carried electricity generators, water and food.
The channel said the convoy's precise route had been kept secret until the last minute for security reasons.
Russia first sent an aid convoy of more than 200 trucks in August without the final agreement of Ukraine and Red Cross monitors.
The second Russian humanitarian aid shipment was delivered earlier this month.
Hundreds of thousands of people in Ukraine's war-battered east are suffering from shortages of basic supplies, a lack of running water and power due to widespread destruction from heavy shelling.
The European-brokered ceasefire sealed on 5 September has scaled back the fighting across eastern Ukraine but deadly shelling and gunfire is reported almost daily around Donetsk.