The United States has added the Pakistani militant group Jamaat-ur-Ahrar to its list of global terrorists, triggering sanctions against a faction that has staged multiple attacks on civilians, religious minorities and soldiers.

Jamaat-ur-Ahrar has claimed responsibility for at least five major attacks in Pakistan since December, including the Easter Sunday bombing in a public park that killed 70 people in the city of Lahore.

The group is a splinter faction of the Tehreek-e-Taliban Pakistan (TTP) that has also declared loyalty to the leadership of Daesh (Islamic State) in the Middle East.

It also claimed responsibility for the killing of two Pakistani employees of the US Consulate in the northwestern city of Peshawar in March.

The designation by Washington means anyone who supports Jamaat-ur-Ahrar could have their assets frozen by the US government.

Pakistan welcomed the decision.

"Pakistan has long pleaded to take concrete action against the TTP and their like who operate in Afghanistan, and they have planned and launched a number of attacks in Pakistan while operating from there," Foreign Office spokesman Nafees Zakaria told a briefing.