United Nations Secretary-General Ban Ki-moon urged the government of Pakistan to reinstate its moratorium on death penalty and stop the execution of convicts, according to a statement released by the U.N. on Friday. Pakistan had lifted its unofficial six-year moratorium on death penalty after a Taliban attack on an army-run school in Peshawar killed nearly 150 people, including over 130 children.

“The Secretary-General spoke on the phone with H.E. Mr. Muhammad Nawaz Sharif, Prime Minister of Pakistan, on 25 December 2014,” the U.N. said in the statement. “While fully recognizing the difficult circumstances, the Secretary-General urged the Government of Pakistan to stop the executions of convicts and re-impose the moratorium on the death penalty.”

Pakistan has so far executed six people since the moratorium was lifted last week. Senior government officials had earlier claimed that the government has drawn up a list of 500 convicts who would be executed in the coming weeks.

International human rights groups have condemned the Pakistani government's decision, reportedly stating that executing prisoners will not protect civilians in the country. Human Rights Watch, in a statement released last Saturday, said that the government was indulging in a “vengeful blood-lust” instead of attempting to find those responsible for the school massacre.

“The government’s death penalty spree is a craven politicized reaction to the Peshawar killings that will do nothing to bring the attackers to justice,” Human Rights Watch’s Deputy Asia Director Phelim Kine said, in the statement.

The U.N. appeal follows a similar statement issued by the U.N. High Commissioner for Human Rights Zeid al Hussein, in which he termed the resumption of executions in Pakistan as "unfortunate" and "disappointing."

“The crime rate, historically, is not lowered by the imposition of capital punishment … instead, shocking cases emerge, with tragic frequency, of the execution of people who are subsequently proven innocent,” Zeid said, in the statement.