Afghanistan's intelligence agency says it has arrested a would-be suicide bomber who planned to detonate his explosives at the funeral of an antigovernment protester in Kabul.

At least seven people were killed on June 3 when three suicide bombers blew themselves up at the funeral of Salem Izadyar, the son of a senator and one of the five victims of the deadly clashes between police and protesters a day earlier.

Deadly antigovernment protests erupted after the May 31 morning rush-hour bombing in Kabul that killed at least 90 people and wounded more than 460, most of them civilians.

Police have locked down much of Kabul city, with armed checkpoints and armored vehicles patrolling the streets, although several dozen protesters on June 4 continued a peaceful sit-in near the blast site.

The demonstrators have called for the resignation of the national unity government, which has failed to curb deadly militant attacks in the capital.

The National Directorate of Security (NDS), the country’s main intelligence agency, said in a statement on June 4 that it had arrested a fourth suicide bomber who failed to detonate his explosives at the funeral in Kabul.

The NDS published a photo of Sayed Rahman, the failed suicide bomber, on their Facebook page.

The intelligence agency said the suicide bombers had all hidden explosives in their shoes and had been trained at the Mawlawi Ahmad madrasah, or religious school, in the southwest Pakistani city of Quetta.

The NDS has also blamed the Kabul bombing on May 31, the deadliest in the city since the U.S.-led invasion in 2001, on the Pakistan-based Haqqani network, which is allied to the Afghan Taliban.

PHOTO GALLERY: Massive Blast Hits Kabul's Embassy District (click on gallery to open)

No group has so far claimed responsibility for the two deadly attacks in Kabul, with the Taliban denying any involvement.

The attacks were the latest in a long series of high-profile militant attacks that have killed hundreds of civilians in Afghanistan since most international forces left the country in 2014.

In the first three months of the year at least 715 civilians were killed across the country, after almost 3,500 last year -- the deadliest on record for Afghan civilians.

The uptick in violence comes as U.S. and coalition officials are working on plans that are expected to bring about an increase of between 3,000 and 5,000 in the number of foreign troops in Afghanistan.

With reporting by Tolo News and Khaama