A suspected U.S. drone strike has killed a self-proclaimed Islamic State in Iraq and al-Sham (ISIS) leader in Afghanistan's eastern Nangarhar province, the Afghan national intelligence agency has claimed.

Former Pakistani Tehreek-e-Taliban commander Hafiz Sayed was appointed as leader of ISIS in southern Asia and the sub-continent where he called his group ISIS Khurasan state.

While the United States officials declined to confirm it, Afghan authorities said an American airstrike Friday killed Islamic State affiliate leader Hafeez Sayeed and more than 30 other militants. That comes after Afghan officials earlier said another U.S. airstrike killed the affiliate's second-highest official, Gul Zaman, and six others, including a former Pakistani Taliban spokesman named Shahidullah Shahid who earlier had joined the group.

The National Security Directorate (NDS), the Afghan intelligence agency, said Sayed was killed in an air strike in the Takhto locality of Achin district.

"ISIS leader for Afghanistan and Pakistan (Khurasan state), Hafiz Sayed and 30 of his fighters were killed in a U.S.-led coalition force's drone strike in Achin, Nangarhar," the NDS said in a statement on Saturday.

"The attack was conducted based on intelligence cooperation between NDS and coalition forces," it added.

NATO officials declined to immediately comment on the claim, saying they would issue a statement later Saturday. U.S. Army Col. Brian Tribus, a spokesman for U.S. Forces-Afghanistan, confirmed Americans carried out an airstrike Friday in Nangarhar's Achin District, but declined to comment further.

At least 100 ISIS fighters in eastern Nangarhar province have been killed in the past two weeks after U.S. forces began a campaign targeting members with drone strikes.

However, alleged links between former Taliban groups in the region and ISIS in Syria and Iraq have been difficult to quantify.

Kabul police chief Abdul Rahman Rahimi said that at least two members of a family, including a child were also injured in the incident.

"Apparently, the explosives-laden vests of the two suicide bombers went off while they were riding towards their target," Rahimi said.

Separately, at least three children were killed and six others were injured in a bomb blast near a petrol pump station in southern Kandahar city at 4 p.m. on Saturday, provincial police spokesman Zia Durani said.

The group's fighters are thought to be former Taliban militants who have rebranded themselves following territorial gains by ISIS in Iraq and Syria over the past year.

ISIS number two in Afghanistan, Gul Zaman and former Pakistani Taliban spokesman, Mawlawi Shahidullah Shahid - who was first to declare allegiance to ISIS leader Abu Bakr al-Baghdadi - were killed by U.S. drone strikes in Nangarhar last week.