A senior Islamic State commander has been killed by an air strike in eastern Afghanistan, intelligence officials said on Saturday, the fourth high-ranking member of the militant group to be killed in the area in the past week.

Hafez Saeed was the leader of Islamic State in the "so-called Khorasan state," according to Afghanistan's National Directorate of Security (NDS), referring to an old term to describe Afghanistan and Pakistan.

He was killed along with 30 other militants as they gathered in Achin district of Nangarhar province late on Friday, the intelligence agency said. It did not give any further details about the air strike.

Saeed, a Pakistani, was among a small but increasing number of senior Taliban militants who have switched allegiance to Islamic State in Afghanistan.

Such figures have been targets for U.S drone strikes, which have killed three other Islamic State commanders in the same area in the past week, including Shahidullah Shahid and Gul Zaman.

After pushing out the Taliban insurgents, Islamic State fighters have in the past two months gained ground in several districts of Nangarhar province, which shares a long and porous border with lawless areas inside Pakistan.

Achin fell to the ISIS militants last month after heavy clashes with the Taliban.

(Reporting by Mirwais Harooni; Writing by Hamid Shalizi; Editing by Pravin Char)