Frustrated negotiators enter the final day Friday of a halting round of crunch UN talks to forge a workable draft for a climate rescue pact to be inked by the year's end.

Diplomats have lamented the "snail's pace" of this week's haggle in Bonn, accusing one another of rehashing well-rehearsed positions and holding up the real work of line-by-line text bartering.

Friday will be the sixth-to-last negotiating day, with five more to follow in October, before the highly-anticipated November 30-December 11 UN conference opens in Paris in the presence of heads of state.

Delegates said the Bonn preparatory round, which opened Monday, made piecemeal progress on some of the detailed discussions, but the overall objective of a universal deal remained far off.

Developing countries, in particular, were disappointed that the working document produced in Geneva in February -- a laundry list of often contradictory options for solving the pressing problem of global warming -- was still essentially the same.