G8 leaders agreed in their initial discussions at Camp David on Friday that Iran needs to disclose more about its nuclear ambitions and that it was time to focus on a political transition in Syria, a U.S. official said.

The leaders, including newly elected French President Francois Hollande and Russian Prime Minister Dmitry Medvedev, also stressed North Korea needed to adhere to international norms on nuclear issues and said it would face more isolation if it "continues down the path of provocation," the official said.

The Friday evening dinner, hosted by U.S. President Barack Obama, was the first opportunity for the G8 leaders to discuss global security concerns. They will talk about the euro zone crisis and other economic issues, including oil market pressures at the summit on Saturday.

The U.S. official described "a sense of optimism" about conditions in Myanmar, and said the leaders gathered at Camp David, in the Maryland countryside, pledged to cooperate on providing aid to the former Burma.

The Camp David summit comes days before the next round of Iran talks, to be held in Baghdad. The G8 leaders "affirmed the importance of having a uniform effort in approaching those Baghdad talks next week," the U.S. official said.

"Each of the leaders noted the urgency for Iran to take concrete steps to assure the international community of the peaceful purpose of its (nuclear) program," the official said.

On the crackdown by Damascus, the official described broad agreement on "the need to move rapidly toward a plan for political transition within Syria" and said that while Medvedev did not outright support that call, he did not oppose it either.

Medvedev is standing in for Russian President Vladimir Putin at the Friday-Saturday G8 meeting, which also draws together leaders from the United States, Canada, Britain, France, Germany, Italy and Japan.

At the end of the Friday night dinner, Obama had a chocolate birthday cake delivered for Japanese Prime Minister Yoshihiko Noda, whose birthday is on Sunday. The G8 at Camp David will end on Saturday afternoon, at which time Obama and several of the other leaders will head to Chicago for a NATO summit.