U.S. Defense Secretary Leon Panetta says Iran is trying to develop and train a militia in Syria to fight on behalf of Syrian President Bashar al-Assad's government.

Panetta also said Tuesday he is confident the United States could enforce a no-fly zone over Syria, but that it was not a “front burner issue” .

His comments come as foreign ministers of the 57-member Organization of Islamic Cooperation are holding a summit in Mecca after agreeing to recommend suspending Syria from the group. The foreign minister of Iran – one of Syria's strongest allies – said his country will never accept the proposal.

Meanwhile, the former Syrian prime minister who defected to Jordan says President Bashar al-Assad's government is on the verge of economic and moral collapse and controls no more than 30 percent of the country's territory.

Riad Hijab's comments came Tuesday in his first public appearance since he defected to the opposition earlier this month.

In Syria, the United Nations humanitarian chief Valerie Amos met with Syrian government officials to discuss ways to boost relief efforts to civilians caught up in the conflict. She also is due to meet with the Syrian Red Crescent.

In China, the country's foreign minister is scheduled to hold talks with a special envoy sent by President Assad. China says it is also considering inviting opposition members to visit.

China has joined Russia in vetoing U.N. Security Council resolutions threatening Syria with sanctions for using heavy weapons against civilians.