A lesser-known militant group " Ahrah-ul-Hind" claimed responsibility for Monday's deadly attack on a district court in Pakistan's capital Islamabad that left 11 people dead and 27 others injured.

Local media quoted the spokesman of the independent group as saying that they would continue attacks until their goals were achieved.

The spokesman said his group was strongly opposed to peace talks between Pakistani Taliban and the government.

"We do not endorse the ceasefire and peace talks between the government and the Taliban as we consider it against Islam," he said.

"We only want implementation of Sharia but the ongoing peace talks have not mentioned it," he said.

Interior Minister Nisar Ali Khan told the National Assembly, the lower house of parliament, that two attackers entered the district court at 9:05 a.m. (local time), opened indiscriminate fire and hurled hand grenades at people before detonating their explosive-laden jackets, killing 11 people including a judge and several lawyers.

An eyewitness Muhammad Imran told Xinhua that around two to three attackers covering their automatic guns with shawls entered the court and started firing and threw hand grenades.

Another eyewitness said, "Militants arrived in a jeep which they parked outside the court building, and stormed into the court, killing everyone who came in their way."

Policemen who were on duty nearby rushed to the site and engaged the assailants. Upon arrival of policemen one of the attackers entered a court room of a judge named Rifaqat Ahmad Awan and blew himself up.

The second attacker threw hand grenades at the policemen who were chasing him. He fell down after getting injured, but he detonated his explosive vest as a policeman approached him.

Some local Urdu TV channels quoted sources as saying that the militants launched the attack to release their accomplices.

According to some reports, around four to six militants attacked the court, while two of the attackers blew themselves up, others fled the scene upon police arrival.

A lawyer Raja Sheraz Janjua told Xinhua that it was the worst day of his life as he had lost many of his colleagues in the attack.

The injured were rushed to the Pakistan Institute of Medical Sciences where a spokesperson Ayesha Isani said that the death toll might further rise as several of the injured were in critical condition.

Pakistan Bar Council, a countrywide lawyers organization, announced to observe mourning day on Tuesday.

Pakistan's President Mamnoon Hussain and Prime Minister Nawaz Sharif condemned the attack.

Sharif also chaired a high-level meeting and discussed the anti- terrorism strategy after the attack.

The Chief Commissioner of Islamabad formed a Joint Investigation Committee comprising intelligence and police officials.

The attack took place a day after Pakistani government decided to halt airstrikes against Taliban hideout in response to a one- month ceasefire declared by the Tehrik-e-Taliban Pakistan (TTP) on Saturday to revive peace talks.

TTP spokesman Shahidullah Shahid disowned the attack, saying they would not be responsible for any violence during the month- long ceasefire.

"We have already issued instructions to all of our colleagues to stop all violent activities. We will have no link with any incident during this period," Shahid said in a statement.

"The Tehrik-e-Taliban is neither involved in the Islamabad attack nor any of our colleagues took part in it," he said.