The prominent lawyer and human rights activist Asma Jahangir, a former chair of the Human Rights Commission of Pakistan and winner of the "Alternative Nobel Prize," died of a heart attack on Sunday in the city of Lahore, her family said.

Jahangir, 66, was hospitalized after having a cardiac arrest, but doctors were unable to revive her, according to a statement from her daughter, Munizae Jahangir.

Born in Lahore in 1952, the popular lawyer was known for championing human rights as well as her role as chairperson of the HRCP, the leading human rights organization in the country, and as a United Nations Special Rapporteur on Freedom of Religion.

"She had such a powerful voice and influential personality and was still a great support in trying to promote and protect human rights," HRCP chairperson Mehdi Hassan told EFE.

Hassan also praised Jahangir for her critique of Pakistan's security agencies and her defense of fundamental rights, for which she was threatened, assaulted in public and even placed under house arrest in 2007 during the regime of Gen. Pervez Musharraf.

In a statement, Pakistani Prime Minister Shahid Khaqan Abbasi expressed grief at Jahangir's demise and lauded her "immense contributions toward upholding rule of law, democracy and safeguarding human rights."

In addition to receiving the 2014 "Alternative Nobel Prize," which is awarded by the Swedish Right Livelihood Award foundation, Jahangir won the 2010 UNESCO/Bilbao Prize, among others.

She was also the first woman to serve as the president of the Supreme Court Bar Association of Pakistan.