COP15 negotiations were once again brought to a halt today when poor nations walked out of a morning plenary, accusing developed countries of ignoring their calls for greater emissions cuts and engaging in a secretive process that leaves no possibility for agreement.

Sudanese Diplomat and chief negotiator for the G77 nations Lumumba Stanislaus Di-Aping, explaining the walk out, told the BBC’s Radio 4: "It has become clear that the Danish presidency – in the most undemocratic fashion – is advancing the interests of the developed countries at the expense of the balance of obligations between developed and developing countries."

He continued: "The mistake they are doing now has reached levels that cannot be acceptable from a president who is supposed to be acting and shepherding the process on behalf of all parties."

The Bolivian delegation, in an afternoon press statement, said of the negotiations: "We are asking for a transparent democratic and inclusive process. It seems negotiators are living in the Matrix, while the real negotiation is taking place in the ‘Green room,’ in small stealth dinners with selective guests."

Talks eventually resumed late this afternoon, yet the walkout reveals the extent to which a final, agreed upon deal is in jeopardy. Not only do rich and poor countries disagree over issues of emissions cuts and finance, but the negotiation process itself is now being increasingly called into dispute.

Several international NGOs, which have been quick in recent days to issue statements on breakdowns in talks, were noticeably silent about the morning’s stalled negotiations. Talks have reached such a delicate stage that few NGOs want to be seen as tipping the balance.

After several hours of delay, the U.S. delegation finally held its daily press conference late this evening. Todd Stern, Special Envoy for Climate Change and head of the U.S. negotiation, talked up Energy Secretary Steven Chu’s announcement early today of increased U.S. commitments to financing clean energy production and, he said, important progress had been made during weekend negotiating sessions.

Yet, little of Stern’s briefing spoke to the fundamental complaints of developing economies such as India and China or those of poor and low-lying countries.

Each day the divisions between negotiating blocs are deepening – over the substance of talk, but also over the tone of them.

At the moment, this is looking less like the push and pull of a typical, contentious negotiating process and more like a dead-end street. There are only four days left of negotiations – two before heads of state arrive – and a breakthrough seems unlikely.

So who will be held to blame?