Thierry Charlier, Associated Press
Tuvalu's Prime Minister Apisai Lelemia addresses the Committee on Development of the European Parliament on "Climate Change and its Effects on Small Island Developing States" at the European Parliament in Brussels Thursday.

BRUSSELS — Western European nations struggled to convince their poorer eastern neighbors Thursday to present a united front on climate change by helping pay developing nations to cut emissions and adapt to climate change.

The European Union casts itself as the world's leader of efforts to combat climate change. It has pledged to cut 20 percent of emissions from 1990 levels by 2020 and says it will increase that to 30 percent if other major polluters make similar commitments at the climate summit in Copenhagen.

But eastern EU nations grappling with the fallout of the economic crisis are reluctant to participate in another key European measure: offering financial help to impoverished developing nations respond to climate change.

Greenpeace activists surprised security at the summit, emerging from a gray Mercedes minivan at the official entrance just as EU leaders were arriving.

"EU leaders must show leadership!" one shouted, while two others jumped out with yellow flags reading "EU Save Copenhagen." Security officials quickly whisked them away.

Western diplomats at the EU's final summit of 2009 were trying hard to convince eastern nations to participate even symbolically in the fund, which is intended to help developing nations to start cutting emissions before a new climate treaty being negotiated in Copenhagen comes into force in 2012 and cope with the effects of climate change.

Failure to persuade the poorer EU nations to contribute would tarnish the appearance of EU unity on climate change, but is not expected to hold up the fund.

"I will definitely ask for contributions" from all countries, Swedish Prime Minister Frederik Reinfelt, whose country holds the EU's rotating presidency, said ahead of Thursday's talks. "Europe should take its fair share" of the $5 billion to $7 billion a year target sum for 2010-2012, he said, adding that he was hoping to come up with a collective sum "tonight."

Sweden's minister for european affairs, Cecilia Malmstrom, said, "We have been encouraging for the last weeks, days and hours all countries to come up with at least a small contribution."

"We are aware that some countries are under extreme economic pressure, of course. But even small contributions can show that all European countries want to contribute and that we have a figure," she said.

The EU is expected to announce a figure Thursday night, but in an apparent attempt to preserve the bloc's perceived unity, it will not break down the amount into national contributions.

It already is clear that wealthy countries will take the lead; Britain has announced it will contribute $1.3 billion over three years, and Sweden will give euro800 million ($1.2 billion). The Dutch say they will contribute euro300 million ($442 million) over three years.

The two-day summit is the first since EU-wide reform known as the Lisbon Treaty entered force this month, bringing new rules to accelerate decision-making. Leaders huddling for the first time without their usual armies of advisers to thrash out decisions on climate change and international banking supervision. On Friday, they will discuss the West's nuclear standoff with Iran and Tehran's violent suppression of pro-democracy protests.

Before the summit got under way, British Prime Minister Gordon Brown and French President Nicolas Sarkozy agreed that executive bonuses should be taxed more and called in an article in the Wall Street Journal for "a new compact between global banks and the society they serve."

The Brown-Sarkozy byline appeared to heal a rift in Anglo-French relations that opened over the appointment last month of Frenchman Michel Barnier to oversee EU financial markets, including the City of London, a powerhouse of world finance.

The summit could also push for a new tax on financial market transactions to help poor countries with climate change. Brown and French Foreign Minister Bernard Kouchner have both pushed for that and are hoping to get all 27 EU nations on board at the summit.

AP writers Raf Casert in Brussels, Angela Charlton in Paris and Geir Moulson in Berlin contributed to this article.