Illinois Senator Barack Obama is on his way to Europe, the next stop in his international trip intended to bolster his foreign-policy credentials, CNN reported Thursday.

The presumptive Democratic presidential nominee is expected to first give a speech in Germany's city of Berlin.

Obama has just left Israel after a pre-dawn visit to one of Jerusalem's holiest sites, the Western Wal, where dozens of people were waiting for him although the visit was not announced in advance.

"Obama, Jerusalem is not for sale," a man screamed when Obama bowed his head and placed his hand on the wall.

Obama has already visited Jordan, Kuwait, Afghanistan and Iraq. He has said he is making the trip as a senator from Illinois and not a presidential candidate.

He said he would be willing to meet with any leader if he thought it would promote the national security interests of the US.

"My whole goal in terms of having tough, serious direct diplomacy is not because I am naive about the nature of any of these regimes. I am not," Obama said. "It is because if we show ourselves willing to talk and to offer carrots and sticks in order to deal with these pressing problems, and if Iran then rejects any overtures of that sort, it puts us in a stronger position to mobilize the international community to ratchet up the pressure on Iran."

After Obama's remarks, Senator John McCain's campaign accused the Democrat of shifting his position and said his comments show "his refusal to admit a mistake about what he said."