By REUTERS

VALPARAISO, Chile (Reuters) - Chile's Senate passed constitutional reforms on Wednesday that cut the presidential term to four years from six and curb military power enshrined in the constitution by former dictator Augusto Pinochet.

The left-center government, in power since 1990, long pushed for the reform, saying it was key to complete Chile's transition to democracy after the 1973-1990 military regime.

The reforms eliminate 10 appointed senate seats -- including ex-military chiefs and former cabinet ministers -- leaving the upper house with 38 members, all elected.

``This is an important step that will allow for the modernization of the (19)80 Constitution, which was in need of changes to institutions that have already served their purpose,'' said Sen. Sergio Fernandez, a former Pinochet minister and a co-author of the 25-year-old Constitution.

The Senate already passed most of the reforms in October, and on Wednesday approved small changes made in the lower house. The reforms are now set for a symbolic approval vote in a joint session, then go to President Ricardo Lagos for signing.

When the center-left came to power in 1990 it had to tread carefully with its reform agenda to avoid antagonizing the ousted military.

``What seemed impossible 10, 15 years ago, today is possible,'' said Interior Minister Francisco Vidal, one of the main executive branch negotiators on the reforms.

The reforms restore presidential power to remove commanders of the four branches of the armed forces, and eliminate potential military meddling with appointees to the tribunal that interprets Chilean law and influences Congress and presidential decrees.

Chile has become a model of political and economic stability in the region since democracy was restored, while Pinochet, 89, has lost political clout and faces hundreds of human rights charges stemming from military abuses.

But his 1980 constitution, designed to keep him in power indefinitely, continued to limit democracy by giving the military a role in checks and balances.

``We've made an important step in making a much more democratic Constitution than the one we have and that's a triumph for the country,'' Vidal said.