Mexico's climate negotiator issued a tearful plea Friday to UN colleagues to put aside their differences for a global pact, as a superhurricane headed for his country.

"In about four hours, Hurricane Patricia will hit the Mexican coast," Roberto Dondisch said at the closing session of a fraught round of negotiations in Bonn. "I don't think I need to say more about the urgency to get this deal done."

"I ask you all to put aside your differences so together we can start working."

Dondisch made the plea on the final session of a five-day effort to advance towards a post-2020 UN pact to tame greenhouse gases.

The negotiations are the last official round before a November 30-December 11 conference in Paris that aims to seal the historic deal.

But the complex process has been hampered by a squabble between rich and developing nations about burden-sharing.

One of the biggest areas of dispute is about a pledge, made by rich economies in 2009, to muster financial help for poor countries badly exposed to rising seas, drought and flood.

Mexico's Pacific coast is set to bear the brunt of a monster hurricane, named Patricia, packing maximum sustained winds of 325 kilometers (200 miles) per hour, according to the US National Hurricane Center.