Libyan human rights lawyer Salwa Bugaighis, who was part of the country's 2011 revolution that ousted the regime of Muammar Gaddafi, has been gunned down by assailants in the eastern city of Benghazi.

A security official told AFP that "unknown hooded men wearing military uniforms" attacked the woman in her home and shot her several times. She was taken to the hospital in critical condition where she died shortly afterwards.

A family member said her husband, who was in the house at the time of the attack, has disappeared.

Bugaighis played a key role in the country's botched transition to democracy. A former member of the National Transitional Council, the rebellion's political wing, she was vice-president of a preparatory committee for national dialogue in LIbya.

The activist helped organise peaceful demonstrations outside Benghazi's courthouse on 17 February 2011, which paved the way for the revolution. The pro-democracy protests started when Fathi Terbil, a fellow lawyer, was arrested.

The US ambassador to Libya, Deborah Jones, called the news "heartbreaking" and denounced on Twitter a "cowardly, despicable, shameful act against a courageous woman and true Libyan patriot".

Bugaighis was pictured yesterday voting in Libya's general election.

The UN support mission in Libya condemned the assassination and called on Libyan authorities to investigate the killing.