"Thanks be to Allah, 43 apostates were killed and around 30 were wounded in an attack carried out by Islamic State soldiers on a bus transporting Shiite Ismaili infidels in the city of Karachi," the extremist group said in a statement posted on “jihadist” Twitter accounts.

It was the first official claim of responsibility by the ISIS leadership of an attack in the Afghanistan-Pakistan region.

ISIS, which has seized control of Parts of Syria and Iraq, announced in January the creation of a branch in what it called "Khorasan province", encompassing Afghanistan, Pakistan and parts of surrounding countries.