NICOSIA, Cyprus (AP) _ The Grand Ayatollah Ali Araki, supreme leader of the world's 100 million Shiite Muslims, has died, Iranian radio reported. He was at least 100 years old.

The broadcast, monitored in Cyprus, announced late Tuesday that ''his eminence Grand Ayotollah Araki bade farewell to the living world after a long illness despite the efforts of doctors.''

Araki was admitted to Tehran hospital's intensive care unit three weeks ago.

The Iranian government issued a statement expressing its sadness at Araki's death and announced a week-long period of mourning.

Even before Araki's death, Iran was trying to influence the selection of his successor in an attempt to enforce its own version of militant Islam.

Araki was designated the marja ala, or supreme leader, of Shiite Muslims around the world only last year, after the death in quick succession of two other supreme leaders of the sect.

Araki's exact age was unknown, since birth records did not exist at the time of his birth. He possibly was as old as 106.

He had lived and taught in the Iranian city of Qom, the center of Shiite learning, for most of his life.

Shiites, who make up about 10 percent of the world's 1 billion Muslims, are the predominant sect in Iran and the majority in Iraq and neighboring Azerbaijan. Small numbers also exist throughout the Muslim world.

As spiritual leader of the world's Shiites, Araki was regarded as the supreme spiritual force. In theory, he had the last word on all matters pertaining to the sect.

But Araki kept a low profile, and avoided the day-to-day affairs of Iran's theocratic government.

Araki's death was likely to split open the issue of succession, since Iran has indicated that the next marja ala must be an Iranian.

To the outside world, the Shiites' marja ala has been eclipsed by lower- ranking clergymen, such as the late Ayatollah Ruhollah Khomeini, patriarch of Iran's 1979 Islamic revolution.

But to Shiites, the marja ala is also a potential challenger of the Tehran government, both at home among Iran's overwhelmingly Shiite population of 60 million and abroad, where Iran seeks to export its revolutionary zeal.

Traditionally, the marja ala is selected from among the Shiite sect's top clerics, or grand ayatollahs. At present, there are at least five grand ayatollahs.

Shiites believe that Ali, the cousin and son-in-law of Islam's Prophet Muhammed, should have succeeded Muhammed as the spiritual leader of Islam. Sunnis, who worldwide are the majority, believe that elected leaders through a Caliphate should have carried on the message.