The head of the International Atomic Energy Agency said Monday that he cannot guarantee that Iran is not trying to develop atomic arms.

Speaking at the start of a 35-nation IAEA board meeting, Yukiya Amano, who heads the UN nuclear watchdog, said he cannot give Iran's nuclear program a clean bill of health because Tehran is refusing to cooperate with an IAEA probe of its programs.

Amano also said that Syria is stonewalling an investigation of a site suspected to have been a secretly built reactor that would have produced plutonium once finished. Israeli warplanes destroyed that structure three years ago.

On Sunday, western diplomats said that Iran and Syria's alleged nuclear activities are high on the agenda for the IAEA board meeting in Vienna on Monday, but no action against them is expected to take place for now.

The IAEA recently received new information concerning possible military nuclear activities in Iran, it said in a report late last month, without giving details.

The report also highlighted previous allegations about seven Iranian research or development projects for a nuclear warhead that officials in Tehran have refused to explain. Iran says the intelligence is fabricated.

In its Syria report, IAEA chief Yukiya Amano said the country has not allowed additional inspections either of a suspected nuclear reactor that Israel bombed in 2007, or of three possibly related sites that his inspectors have not yet visited.

The IAEA is aware of intelligence information that one of the sites could have been set up to make reactor fuel, diplomats said.

However, Syria decided one week before the board meeting that it would allow a visit to a fourth location, a civilian chemical plant that produces uranium as a by-product.

While diplomats acknowledged that Syria's blocking undermines the IAEA's authority, they questioned what a resolution or a so-called special inspection would achieve at this point.

A diplomat said Sunday it was difficult to take action on Syria also because of its complex connection with Middle Eastern politics, referring to the tendency of developing countries on the board to support Israel's perceived enemies.

Besides these questions of tactics, diplomats said their capitals are not focused on these two nuclear issues right now, but rather on the political upheavals in the Middle East and North Africa.