NICOSIA, CYPRUS, NOV. 7 (WEDNESDAY) -- A strong earthquake struck a mountainous area of southern Iran Tuesday night, killing at least 20 people and heavily damaging at least a dozen villages, Iran's official news agency reported today.

The U.S. Geological Survey in Golden, Colo., said initial readings put the quake's magnitude at 7.0 on the Richter scale. Iran's Geophysics Center of Tehran University said it measured 6.6.

An earthquake of that magnitude is capable of widespread, heavy damage. A quake measuring 7.7 on the Richter scale struck northern Iran on June 21, killing an estimated 50,000 people.

Tuesday's quake struck at 9:47 p.m. and was centered in Fars province near the city of Darab, about 600 miles southeast of Tehran, the Islamic Republic News Agency said.

IRNA, monitored here, said at least 20 people were killed and more than 60 injured. It quoted Darab Gov. Yahya Hashemi as saying at least 12 villages were heavily damaged.

Earlier reports from the region told of 100 dead and wounded, counted an hour after the quake struck, according to Alireza Jafarzadeh, the Washington, D.C.-based spokesman for the People's Mujahedeen of Iran.

Jafarzadeh, whose group seeks to overthrow the Tehran government, said he had no breakdown of dead and wounded.

The quake, centered 50 miles east of the city of Darab, hit the route that connects Darab with the port city of Bandar-Abbas on the Strait of Hormuz, said Jafarzadeh.

"This is a mountainous area," he added. "The casualties are high because the quake occurred late at night when most villagers were at home."

In the two counties of Forg and Abshour, he said, "there were a total of 20 villages damaged 50 to 80 percent."

The Richter scale is a gauge of the energy released by an earthquake, as measured by the ground motion recorded on a seismograph. An increase of one number on the scale means a ground motion increase of 10 times.