European Union (EU) leaders will meet later this week on three crucial topics, namely the economic crisis, the climate change and the Lisbon Treaty, the European Commission President Jose Manuel Barroso said on Tuesday.

"This is perhaps the most crucial European Council in recent years. If I may make a personal note, I would say that for me, this is the most important European Council I have participated in as President of the Commission," Barroso told a pre-summit press conference in Brussels on Tuesday, using the official name of the EU leaders' meeting.

As the EU economy is plunging into a recession due to the financial crisis, EU leaders are due to draw on a commission proposal to hammer out a coordinated response to the economic crisis.

"We have put on the table of the European Council an ambitious and realistic economic recovery plan. A plan that combines short term stimulus with medium term stability and long-term growth," Barroso said.

The commission proposed in November a EU-wide economic stimulus package worth 200 billion euros (US$256 billion). The sum amounts to 1.5 percent of the EU's gross domestic product (GDP), with 1.2 percent coming from EU governments and the rest from EU funding.

Barroso urged EU leaders to endorse the overall target of spending 1.5 percent of the EU's GDP to stimulate economy at the summit.

"I will insist on that -- that we have the 1.5 percent target as a sign that we mean business when we are speaking about fiscal stimulus," he said.

However, EU Economic and Monetary Affairs Commissioner Joaquin Almunia said on Monday that member states have not pledged enough on their national fiscal stimulus plans so far.

"It does make some progress but we do not reach the progress we hoped for," he told a committee of the European Parliament in Brussels, adding 18 of the EU's 27 member states had adopted their national fiscal plans more or less in line with the commission's proposal.

Germany, the largest economy in the EU, is facing pressure to expand its national fiscal stimulus plan for the benefits of the EU economy as a whole, but Berlin has resisted the call, saying their current plan worth 32 billion euros (US$41 billion) is enough.

Barroso denied there is fundamental disagreement between Berlin and other EU capitals, indicating German Chancellor Angela Merkel may increase the country's stimulus scale next year.

"I think next year there will be some revisions of the national intentions," Barroso said. "I have no doubt about Chancellor Merkel's intention to make a contribution to the European package."

At their two-day summit, EU leaders also need to fight hard for a compromise on the climate change package.

Barroso called on EU governments to keep their promises on climate change, which will see a 20-percent reduction of greenhouse gas emissions, 20-percent energy savings and 20-percentrenewables in total energy consumption for the EU by the year 2020.

"It is a question of credibility. It would be a real mistake for Europe to give the signal that we are watering down our position, after all these years leading the efforts for a global solution," he said, adding the overall targets are non-negotiable.

Barroso expressed optimism that agreement can be reached at the EU summit on Thursday and Friday.

EU governments have agreed on over 90 percent of the measures contained in the commission's original proposal, but the most thorny issues are left for the heads of state and government to tackle.

Impediments include Poland's concerns that the emissions reduction target will create heavy costs for its power sector, which is almost totally dependent on coal. Italy and Germany also fear that the measures will harm the competitiveness of their industry.

Barroso argued that the current economic difficulties should not be used as pretext to lower the EU's ambitions on climate action.