Image caption Ms Berenson's affiliation with the MRTA has been disputed by her parents

Lori Berenson, an American citizen who has served 15 years in a Peruvian prison for aiding leftist rebels, has been freed on parole.

Ms Berenson, 40, was arrested in 1995 for her alleged role in a plot to attack the Peruvian Congress.

A military court found her guilty of collaborating with the left-wing Tupac Amaru rebel group and sentenced her to life imprisonment, later reduced to 20 years in prison.

She has always denied the charges.

The judge ordered her to stay in Peru for five years in order to serve out the remaining years of her sentence on conditional release.

The daughter of university professors, Ms Berenson broke off her studies at the Massachusetts Institute of Technology in Boston to travel to Central and South America.

'Kidnap plot'

During her travels, she is believed to have made contact with the Tupac Amaru Revolutionary Movement, or MRTA, a Marxist rebel group active in Peru in the 1980s and 1990s.

Tupac Amaru guerrillas became notorious for taking more than 70 people hostage in the Japanese ambassador's residence in Lima in 1996 and holding them for 126 days.

Ms Berenson was arrested after she gained access to the Peruvian Congress on false journalist credentials alongside the wife of MRTA leader Nestor Cerpa.

TIMELINE 1995: Arrested

1996: Military trial, jailed for life

2000: Conviction overturned, civil retrial ordered

2001: Convicted and sentenced to 20 years

2002 Supreme Court upholds sentence

2010: Freed on parole

Military prosecutors accused her of gathering information for a rebel plot to kidnap members of Congress and exchange them for imprisoned rebel leaders.

Her original life sentence was reviewed by a civil court in 2001.

She was convicted on the lesser charges of terrorist collaboration and her sentence reduced to 20 years.

In 2003, Ms Berenson married fellow prisoner Anibal Apari, who was serving 13 years for his affiliation to the same rebel group. She gave birth to their son a year ago. Mr Apari is also her lawyer.

Her parents have been fighting for her release since her arrest and have always maintained her innocence.