COPENHAGEN — U.N. negotiators at the COP15 climate change conference were racing against the clock Tuesday, trying to conclude some form of agreement before nearly 120 heads of state began arriving Wednesday.

Differences over fundamental issues remained, with Japan being accused by developing countries and NGOs of attempting to kill the Kyoto Protocol.

No sign of a breakthrough had been seen as of Tuesday morning on fundamental issues that have divided developed and developing countries since the beginning of the conference last week.