WASHINGTON, USA - Responding to Iran's political crackdown and nuclear program will be "at front and center" of President Barack Obama's visit to Russia and the G8 summit in Italy next week, a US official said.

Denis McDonough, one of Obama's top foreign policy aides, said that the president's visits would build upon a Group of Eight foreign ministers' statement on Iran issued on Friday.

"The issue of Iran will be front and center at each of these stops," McDonough told reporters, looking ahead to Obama's visit to Moscow and the G8 summit in Italy next week.

McDonough said that Obama was "quite gratified" at the role played by Russia in forging the G8 foreign ministers' statement. Moscow had previously commented that the demonstrations were an internal affair.

On Friday, the G8 expressed full respect for Iran's sovereignty but deplored post-election violence there and urged Iran to respect fundamental human rights.