Afghan President Hamid Karzai has cut short a European trip and returned to Kabul, after a deadly attack targeting a Shi'ite shrine
The attack on December 6 killed 55 people and injured more than 160 outside a Shi'ite shrine in Kabul where hundreds had gathered to celebrate a religious holiday.
At least four people were killed in a near-simultaneous bombing in the northern city of Mazar-e Sharif.
The Kabul attack marked the first major assault on Afghanistan's Shi'ite minority in recent years.
Lashkar-e Jhangvi, a Pakistan-based group, has claimed responsibility.
The group is responsible for dozens of attacks against minority Shi'a in Pakistan, but the validity of the claim could not be immediately determined.
Visiting the wounded in the hospital on December 7, Karzai said he would raise the issue with the Pakistani leadership.
His spokesman Aimal Faizi told the AFP news agency that Karzai would "demand Pakistan take executive measures...so that justice can be done."
The U.S. State Department backed the demand, urging Islamabad to crack down against the militant group.
Meanwhile, Pakistani Foreign Ministry spokesman Abdul Basit said Islamabad would encourage Kabul to share any evidence it has that Lashkar-e Jhangvi was responsible.
The attacks came one day after a major international conference in Germany
on the future of Afghanistan.
compiled from agency reports