Pakistan plans to execute 55 people in the coming days, after their mercy petitions were recently rejected by the country's president Mamnoon Hussain, reports say.

Six fighters have been hanged since a Taliban attack on an army-run school in the city of Peshawar last week left 149 people, mostly children, dead, triggering public anger.

Of the six hanged so far, five were involved in a failed attempt to assassinate the then-military ruler Pervez Musharraf in 2003, while one was involved in a 2009 attack on army headquarters, AFP news agency reported on Monday.

After the school attack, Prime Minister Nawaz Sharif lifted the six-year moratorium on the death penalty, reinstating it for "terrorism-related" cases.

According to the Dawn newspaper, it normally takes at least 14 days to hang a convict once his or hers mercy petition is rejected. However, the Punjab government, which is dealing with majority of people on death row, recently made amendments to its laws and reduced the period to two days. It also changed a law under which executions could be carried out only at 4am and now convicts can be hanged any time.

Prime Minister Sharif has ordered the attorney general's office to "actively pursue" capital cases currently in the courts, a government spokesman said.

"Prime Minister has also issued directions for appropriate measures for early disposal of pending cases related to terrorism," the spokesman said.

Pakistan began its de facto moratorium on civilian executions in 2008.

Before the latest resumption, only one person had been executed since the moratorium - a soldier convicted by a court martial and hanged in November 2012.

Source: Al Jazeera and agencies