Reaching out to the Muslim world, President Barack Obama said that the US "is not and will never be at war with Islam" as he sought to rope in close ally Turkey in the critical fight against terrorism.

Addressing a packed Turkish parliament, Obama said: "Let me say this as clearly as I can."

"The United States is not and never will be at war with Islam. In fact, our partnership with the Muslim world is critical ... in rolling back a fringe ideology that people of all faiths reject," Obama said during his first state visit to a Muslim nation after becoming US President in January.

Describing Turkey as a key US ally in many areas, including the fight against terrorism, he said there should be greater bond between Americans and Muslims.

Obama's visit is being closely watched by an Islamic world that harboured deep distrust of his predecessor, George W Bush.

Obama clearly sought to draw a distinction between Islam and terrorist groups like al-Qaeda saying the latter did not represent the vast majority of Muslims.

"America's relationship with the Muslim world cannot and will not be based on opposition to al-Qaeda," he said, adding that the US sought broad engagement based upon "mutual interests and mutual respect."