BRUSSELS (Reuters) - The United States must take another step towards a global climate change pact when major industrialized countries meet in Japan next week, the head of the European Union's executive said on Friday.

"In this G8 summit we will expect the United States to show more ambition than they have shown so far," European Commission President Jose Manuel Barroso told reporters.

"The world expects more from a major economy like the United States," Barroso said. "I am saying that not just as a hope -- I expect the U.S. will accept a more ambitious conclusion at the G8 than the one last year."