"The ceasefire must be confirmed by the official order of President Poroshnko to the Ukrainian army and the National Guard… And this order should be published on Ukrainian president's official website," DPR's Denis Pushilin and LPR's Vladislav Deinego said in a joint statement.
The negotiators added that the immediate ceasefire by Kiev forces is the "first and foremost condition" to continue the negotiations.
On Saturday, the Contact Group on Ukrainian crisis held a fresh round of peace talks in Minsk, the capital of Belarus.
Kiev and representatives of the breakaway republics blamed each other for failing the reconciliation talks in Minsk. Kiev's negotiator Leonid Kuchma argued that the independence supporters had broken the talks down, since the leaders of Donetsk and Luhansk did not show up. In response, Pushilin and Deinego noted that Kuchma was not even officially appointed as a Ukrainian representative at the talks.
Kiev and independence supporters managed to reach a ceasefire deal during the September 5, 2014 Minsk talks. However, the confrontation between the warring parties intensified severely in the beginning of 2015, deemed by the United Nations the "worst hostilities" since the truce was signed.