CAIRO, Egypt (AP) _ Egypt's President Hosni Mubarak inaugurated a new stage of Cairo's subway Sunday that will take trains under the Nile, Egyptian radio reported.

Mubarak pushed the button to start the first train along a three-mile track from downtown Cairo through a 633-yard tunnel under the river to the city's university in the western suburb of Giza, the radio said.

The line is to be extended by next year to a spot near the pyramids and will eventually be about 12 miles long, the government-run newspaper Al-Ahram reported.

The $7 billion subway project has two lines now operating. Its trains carry about 1.7 million passengers a day.

The subway is the only one in the Middle East and Africa.