VIENNA- Prospects for peace in eastern Ukraine are "bleak", underscoring the need to uphold a shaky ceasefire between government forces and pro-Russian separatist rebels, a senior official from the OSCE security watchdog said on ThursdaySwiss diplomat Heidi Tagliavini, the Organization for Security and Cooperation in Europe's envoy to the Trilateral Contact Group that includes senior representatives from Ukraine and Russia, said there was no alternative to peace accords signed in Minsk in September, no matter how dire the situation."Whatever (their) shortcomings may be and wherever they may need to be supplemented, the (Minsk) documents are the door on the road to peace in eastern Ukraine, and they will continue to be so," she told a meeting of the 57-member OSCE in Vienna."I am unable to accept any remarks that the ceasefire arrangements of Minsk have fallen apart. Yes, it has been broken many times but it is the only agreement in place which has any restraining power on the use of force."Fighting in eastern Ukraine has killed an average of 13 people each day in the eight weeks since the ceasefire agreement, U.N. High Commissioner for Human Rights Zeid Ra'ad Al Hussein said on Thursday. At least 4,317 people have been killed and 9,921 wounded since April.