KABUL, May 29: American aircraft bombed southern Afghanistan for the second time this week after two US soldiers were injured in a clash near the border with Pakistan, the US military said on Saturday.

The American troops were wounded in a firefight on Thursday night near Shkin in the border region, US military spokesman Lieutenant Colonel Tucker Mansager told a press conference in Kabul.

"We had two coalition casualties in the engagement that led up to us using ordnance down there," Col Mansager said.

The clash and bombardment took place in rough terrain about 230 kilometres south of Kabul in Paktika province.

It was the second time this week the 20,000-strong US-led coalition has called in an air strike in southern Afghanistan.-AFP