US President Barack Obama says a "new chapter in American diplomacy" has been turned after the Arab Spring uprisings.

In a speech at the state department, Mr Obama said the future of the US was bound to the Middle East by forces of economics, security, history and fate.

Singling out Libya, Syria and Iran, he warned that in too many countries calls for change were being met by violence. He called on Syrian President Bashar al-Assad to allow peaceful protests, and begin a "serious dialogue to advance a democratic transition".