Iraqi Shia cleric Muqtada al-Sadr has urged Syrian President Bashar al-Assad to step down and external parties to withdraw so as to restore peace in the world.

"All the external parties and their forces must withdraw from Syria. I also call on Bashar al-Assad to resign," Rudaw news agency quoted him as saying.

Sadr became the first Iraqi political leader to call on Assad to resign even as he condemned the US for the missile strikes on a Syrian airfield on Friday (7 April).

In a statement he said: "I think it would be fair for President Bashar al-Assad to offer his resignation and step down in love for Syria, to spare it the woes of war and terrorism ...and take a historic, heroic decision before it is too late."

He added that the US intervention would drag the region further into war and could play a role in the expansion of Islamic State militant group.

Shia-led Iraqi governments have maintained good relations with the Syrian government over the course of the last six years and Sadr is one of the only Shia leaders to have maintained distance from Iran, who backed Assad along with Russia.

On Friday, the Iraqi government condemned the chemical attack without naming Assad and called for an investigation. The statement also rebuked the "hasty intervention" by the US, which launched missiles on the Syrian airbase following the chemical attack.

Meanwhile, US Ambassador to UN Nikki Haley said in an interview that there could not be a political solution in Syria if Assad remained in power. Her comments come two days after she addressed an emergency meeting at the UN Security council meeting where she said that the US is prepared to take further action.