CANCUN, Mexico – Mexico’s foreign secretary told the global climate conference on Sunday there will be “no hidden text and no secret negotiations” in the meeting’s final days, assuring delegates Cancun will not see a repeat of the last hours of 2009′s Copenhagen climate summit.

“The Mexican presidency will work with full transparency in the coming days,” Foreign Secretary Patricia Espinosa declared at an unusual Sunday session of all parties in the difficult, slow-moving annual talks to find ways to combat climate change.

In closed-door midnight talks at last December’s summit in the Danish capital, U.S. President Obama and a handful of other leaders, including Chinese Premier Wen Jiabao, produced a “Copenhagen Accord,” a document envisioning only voluntary reductions in global-warming gases and disappointing treaty nations ranging from Europe to small island states facing seas rising from global warming.

Dissident delegations led by Venezuela, Bolivia and other left-leaning Latin American governments, unhappy about the closed nature of the decision-making, refused to endorse the U.S.-brokered accord, leaving it without consensus support under the U.N. climate treaty.

Concerns arose of a similar problem here, where environment ministers, not government heads, are gathering to reach decisions in the conference’s second week. Delegates spoke Sunday of a “ghost of Copenhagen” haunting the Cancun talks.

Seeking to dispel such concerns, Espinosa told delegates Sunday that “there will be no separate ministerial process” — that any smaller-scale consultations involving the ministers would be closely meshed with the full, 193-nation negotiation scheduled to end next Friday.

“I must say that there is no hidden text and no secret negotiations,” she said.

The Cancun talks, at best, may produce decisions on side matters under the treaty: establishing a “green fund” to help poorer nations rein in greenhouse gases; an agreement making it easier for developing nations to obtain patented green technology from advanced nations; pinning down more elements of a system for compensating developing countries for protecting their forests.

What will not be resolved at Cancun is the core dispute in the climate talks: the issue of reducing carbon dioxide and other greenhouse gases emitted by industry, vehicles and agriculture.