The Federal Bureau of Prisons plans to build a detention center for illegal aliens in the central Virginia county of Prince George, bureau director Norman Carlson said yesterday.

The 1,000-bed facility will be a scaled-down version of the illegal alien detention center federal officials had proposed for Bainbridge, Md., last year. Plans to build that facility, which would have held more than 2,000 illegal aliens, were later scrapped in the face of local opposition.

Instead, the Bureau of Prisons now wants to build two detention centers -- the Prince George facility, which will hold illegal aliens apprehended in the Eastern half of the United States, and a similar 1,000-bed facility in El Reno, Okla., which will hold those from the West, said a Justice Department spokesmen.

The Prince George detention center would be built on a government-owned 80-acre site next to a Bureau of Prisons correctional facility for youthful offenders, said a Bureau spokesmen. He said the illegal alien detention center will benefit from its closeness to an existing federal facility because "we have experienced staff" there.

Carlson, who made the announcement in a meeting with local officials yesterday, said that the facility would cost $15.5 million and create about 350 jobs. He said he would like construction to start by mid-1983 so the facility could be open by 1985.

One local Virginia government -- the Petersburg City Council -- has gone on record opposing the detention center, said Rep. Robert W. Daniel Jr. (R-Va.), who represents the area. He said two other jurisdictions involved, Hopewell and Prince George County, have yet to consider the matter.

Daniel said he will wait for those reactions before taking a position on the plan.