TEHRAN - A doctor who died at the Kahrizak detention center, closed after the deaths there of several protesters against June's disputed election, committed suicide, state media said on Wednesday.

Iran's parliament has begun an investigation into the death last week of Ramin Pourandarjani, who was serving his military service as a doctor at the facility.

The death of Ramin Pourandarjani was the result of suicide, the official news agency quoted police chief Esmail Ahmadi-Moghaddam as saying.

The doctor had complaints of being threatened with a five-year jail term and had lost his spirit, he said, referring to an apparent will Pourandarjani had written.

He committed suicide after he was summoned to the court.

Kahrizak was closed in July on orders of Supreme Leader Ayatollah Ali Khamenei after at least three people, arrested during the post-election unrest, died in custody there.

Thousands of people were arrested in the protests after the June presidential election which led to the victory of Mahmoud Ahmadinejad. Moderate opposition candidates said the vote was rigged, a charge that Khamenei and the government have rejected.

The protests have proved the toughest domestic test to Iranian authorities since the Islamic revolution of 1979.

Reformist opposition websites reported last week that the death initially was thought to be a result of suicide.

A member of parliament's health committee said on Tuesday death due to a heart attack was unlikely because of no previous health problems and Pourandarjani's age, said to have been 26.

(Writing by Reza Derakhshi, Editing by Michael Roddy)