A campaign aide who helped Iran's reformist Mohammed Khatami win last year's presidential election has begun a six-month prison sentence on charges of libel and publishing lies.

Ali Khaledian said the accusations against him related to a survey he had conducted into the situation in Takab, in north-western Iran, at the request of the former governor-general of West Azerbaijan province.

I prefer to go to prison for the sake of defending the reforms

Ali Khaledian

The defendant was initially found guilty late in 2000 and the sentence was recently upheld by an appeals court.

Iran's conservative-dominated courts have sentenced several politicians allied to Mr Khatami to prison over recent months and closed many newspapers that support him.

Khaledian told the Iranian news agency Irna that he preferred "to go to prison for the sake of defending the reforms and the sacred aspirations of Khatami".

Reforming strict Islamic social codes are at stake

Reform was necessary to safeguard Iran's Islamic revolution, he said.

He said his investigation had fallen "into the hands of Khatami's opponents in the executive organs instead of at the province's governorate".

Khaledian told Irna: "I will continue to do my utmost to disclose the facts, and will never stop short of this mission."

Mr Khatami was re-elected by a 77% landslide a year ago.

But the conservative camp, with the judiciary at the forefront, has done its utmost to thwart the president's programme of relaxing Islamic social rules and promoting greater freedom.