U.S. ambassador to Afghanistan Ryan Crocker said Saturday it was unlikely that this week's deadly attacks on Shi'ites in Afghanistan would spark a cycle of sectarian violence in the country.

The veteran diplomat said that, based on the reaction of the Shi'ite leaders who have called for calm, he did not see the attacks turning into a sectarian conflict.

Two blasts, one in Kabul and another in the northern city of Mazar-e-Sharif, killed at least 59 people Tuesday on Ashura, the holiest day of the Shi'ite Muslim calendar.

Crocker said the attacks had been orchestrated by militants outside of Afghanistan, but that he could not authoritatively say the Kabul bombing was carried out by the outlawed Pakistan-based Lashkar-e-Jhangvi group, even though it has claimed responsibility.

In violence Saturday, a bomb planted on a bicycle killed two people, including a member of Afghanistan's peace council, and wounded 16 others in northern Kunduz province. In the south, a roadside bomb killed three civilians in Kandahar province.

General John Allen, commander of NATO-led coalition forces, joined Afghan President Hamid Karzai in condemning Saturday's attacks. A NATO statement said “innocent individuals, to include children, were again killed and injured at the hands of insurgents.” The statement said that “these insurgents who bring violence against Afghan families are enemies of peace and must be held responsible for their grievous actions.”

Also Saturday, combined Afghan and coalition security forces captured several Taliban and Haqqani leaders and multiple insurgents across the country. A NATO statement said that during the operations, security forces safely destroyed a bomb making factory in central Wardak province, and seized multiple caches of weapons in northern Sar-e-Pul and eastern Paktika provinces.