The Supreme Court of Pakistan has summoned Prime Minister Imran Khan today (Wednesday) in the Army Public School (APS) massacre case.

A three-member bench headed by Chief Justice Gulzar Ahmed is hearing the case.

On December 16, 2014, Tehreek-e-Taliban Pakistan (TTP) militants stormed the Army Public School in Peshawar and gunned down over 140 people, mostly schoolchildren, in cold blood.

A hearing of the case took place today during which the apex court summoned the prime minister to appear before the bench at 11:30am, in his personal capacity.

During the previous hearing of the case, parents of the children martyred in the 2014 terrorist attack had complained to the court that they had lost their children in the incident hence the top civil and military leadership of the country should be summoned by the Supreme Court and cases registered against them.

The victims' parents had also demanded of the apex court to hold a transparent inquiry into the incident. The court had asked the attorney general to review the situation and take necessary steps--whether it be an investigation or filing cases against those responsible-- and inform the court.

When the hearing resumed today, the court asked the attorney general for an update, who responded by saying that FIRs cannot be registered against the top leadership.

At this, the bench angrily told the government's lawyer that the incident had taken place as a result of a "security lapse" which the government should accept, adding that the top civil and military leaders of the time should have known about the attack.

The chief justice then remarked that Pakistan's agencies and institutions have access to all sorts of information but when it comes to the security of the people "our security agencies fail".

Justice Ijaz ul Ahsan said the APS massacre had taken place in response to Operation Zarb-e-Azb, adding that state institutions should have taken effective steps against it.

During the hearing, the attorney general sought time from the court to seek directives from the prime minister and other officials so he can respond to the court.

However, the bench said this was a very serious case and that it would summon the prime minister and seek answers from him.

The attorney general had sought further time for the prime minister to appear before the court. However, the bench expressed anger at his request and said the parents of the victims of the APS massacre are also in court.

The hearing of the case has been adjourned for the time being and will resume by 11:30am.