Pakistani investigators late Monday pointed the finger at the extremist Islamic State group as the death toll from a suicide bombing at a political rally climbed to 46, officials said.

A suicide bomber blew himself up among the crowd at the rally of an Islamic political party on Sunday in Bajaur, a mountainous area near the Afghan border that the Pakistani Taliban once controlled.

At least 40 people died on Sunday, and more than 150 were wounded.

At least six more victims succumbed to their injuries at hospitals overnight, bringing the death toll to 46, rescue official Bilal Faizi said.

Out of more than 150, around 90 injured people were still being treated at hospitals in the north-western province of Khyber-Pakhtunkhwa, Faizi added.

Provincial police chief Akhtar Hayat Khan confirmed it was a suicide bombing, and DNA testing was being conducted to identify the bomber.

At least three suspects were arrested overnight in a possible link with the bombing and were being interrogated by the intelligence and law-enforcement agencies, local police chief Nazir Khan said.

“What we have concluded from the initial investigation is that the attack carries the hallmark of Daesh [Islamic State],” Mr Khan added.

The Islamic State in Khorasan (ISIK), the local affiliate of the extremist group, has been active in Afghanistan and Pakistan since 2015 and has been behind several deadly attacks.

The surge in violence by the Islamist militants ahead of the elections in Pakistan has been a trend since 2008.

(dpa/NAN)