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.

"It will be the policy of the US to promote reform across the region and to democracy," Mr Obama said.

Analysts say the speech was meant as Mr Obama's first comprehensive response to revolts sweeping the Arab world.

Mr Obama was widely expected to defend new sanctions on Syrian President Bashar al-Assad

Some details of the speech were revealed in advance by senior administration officials.

Mr Obama was to stress that Washington stands ready to help nations across the Middle East and North Africa to launch democratic reforms, modernise and provide job opportunities to millions of disenchanted young people.

He was to argue that such measures will help democracy take hold and thrive and deliver the regional stability that is in the interests of the US government.

Analysts say Mr Obama's speech will be aimed at convincing his US audience that the fate of countries in the Middle East and North Africa is worth the money and effort even during difficult economic times at home.

To his wider audience, Mr Obama wants to underline that Washington stands behind those seeking greater human rights.