World Bulletin / News Desk 

A senior U.S. envoy said on Wednesday the growth of the ISIL had global implications and could "wreak havoc on the progress of humanity" if unchecked.

Retired Gen. John Allen, appointed by U.S. President Barack Obama to build a coalition against ISIL, told a conference in Qatar the group was not merely an Iraqi problem or a Syrian problem but "a regional problem trending towards global implications".

Allen said there was no future for Iraq without Sunni support and stressed the need for the government to control the Shi'ite militias, some of whom have links to Iran.

"We said many times that it is critical that all forces in the battle field must be under the command and control of the government of Iraq for the counter-ISIL operation to be successful," he added.

Washington remained "very attentive and concerned about extremist militia elements frequently influenced by Iranian leadership, where Iran may play a significant role in their presence," he said.

He added that Turkey's borders with Syria and Iraq were the "last line of defence" against foreign fighters coming into the conflict - but other countries also needed to help stop the influx.

Bashar al-Assad should have no place in a solution to Syria's war, he added, repeating Washington's stance on efforts to end the fighting.