United Nations (IANS): UN Secretary-General Ban Ki-moon on Monday slammed the terrorist attacks on churches in Lahore that killed 15 people, and called for punishing the perpetrators.

Ban urged the Pakistani government to “swiftly bring the perpetrators to justice and to do its utmost to prevent attacks against places of worship and protect religious minorities”, according to a Xinhua report.

Two powerful explosions on Sunday rocked two churches separated by merely half a kilometre in Lahore’s Youhanabad area, which is home to Pakistan’s biggest Christian population.

Jamatul Ahrar, an offshoot of the Tehreek-e-Taliban Pakistan (TTP), claimed responsibility for the attack in which 15 people were killed and over 70 injured.

Around 500 people were reportedly attending Sunday prayers inside the churches when the terrorists struck.

The UN secretary-general noted with grave concern that the TTP claimed responsibility for the attacks, while threatening to carry out more such acts in the future, said a statement read by UN deputy spokesman Farhan Haq.

Ban extended his condolences to the families of the victims and to the government and people of Pakistan.

The group responsible for the attack vowed to continue attacks “until an Islamic system” was established in Pakistan, according to reports.

The TTP has been waging an insurgency against the state and has targeted mosques, churches and other places of worship. The violence has claimed tens of thousands of lives over the past decade in Pakistan.