One of the most influential clerics in Iran who was once the designated successor of Ayatollah Khomeini has denounced the way that Iran is being run.

Ayatollah Ali Hossein Montazeri, who is under house arrest in the holy city of Qom, accused Iran's conservatives of trying to monopolise power.

In press interviews, he specifically criticised the current supreme leader of Iran, Ayatollah Ali Khamenei, who is backed by prominent conservatives.

Not above the law

Ayatollah Montazeri, a founding father of the Islamic Republic, said the supreme leader could never be above the law.

He criticised the concentration of power held by Ayatollah Khamenei's office, saying his authority should extend only to areas of expertise in religious jurisprudence and not to all matters of state.

"He can never be above the law, and he cannot interfere in all the affairs, particularly the affairs that fall outside his area of expertise, such as complex economic issues, or issues of foreign policy and international relations," Ayatollah Montazeri said.

Timely comments

"And since the supreme leader... is not infallible, he should naturally remain open to public criticism and be held accountable with respect to his responsibilities."

The BBC's Tehran correspondent, Jim Muir says the Ayatollah's criticisms are timely as Iran prepares for general elections next month, in which reformists are hoping to win control of parliament.

Although he did not specifically address the polls, the Ayatollah said the use by the Council of Guardians - an elections supervisory body controlled by conservative clerics - of its screening powers to ban candidates on ideological grounds threatens the legitimacy of Iran's Islamic system.

Reformist struggle

In a faxed interview to Reuters news agency, Ayatollah Montazeri said: "The constitution is explicit that the supervisory role of the Guardian Council pertains to 'supervision over elections" not to 'supervision over the candidates'."

"If such monopolistic tendencies continue, I am afraid the revolution will naturally lose its popular support and, God forbid, will suffer defeat."

Last week dozens of pro-reform candidates were barred from running in the crucial parliamentary elections, which are expected to be a significant test of the reform programme instigated by President Mohammad Khatami.

Correspondents say reformers swept to power in municipal elections in Iran last year but need control of the conservative-dominated parliament in order to push through President Khatami's reform agenda.

'Distorting democracy'

On Wednesday, Ayatollah Khamenei's own brother added his voice to criticism by leading reformist clerics of the disqualification of the candidates.

Addressing students at a Tehran university, Hadi Khamenei said the disqualifications were distorting the nation's vote and Iranian democracy.

This came days after Ayatollah Khamenei rebuked people who had publicly criticised the election vetting process.

Ayatollah Montazeri, one of the prime architects of Iran's constitution, was designated by Ayatollah Khomeini as his successor but fell from favour in 1989 after criticising Iran's treatment of political prisoners.

He was put under house arrest in 1997, and, although his books are banned, they are said to be read clandestinely by thousands of his disciples, the seminarians.