ANN ARBOR, Mich. (AP) _ Students protesting low black enrollment and racial incidents at the University of Michigan ended an overnight sit-in Friday and met with university President Harold Shapiro to discuss their demands.

About 250 demonstrators, including both black and white students, had staged the sit-in at the administration building and blocked its entrances to employees at 7 a.m. But the protesters gave up later in the morning after workers entered through underground steam tunnels.

''The aim we set out to accomplish has been undermined. But they have not undermined our strength,'' said Barbara Ransby, a leader of the student group United Coalition Against Racism. ''This is only one battle. We intend to win the war.''

After leaving the administration building at about 9:45 a.m., about 50 demonstrators disrupted the Board of Regents meeting at a nearby building by occupying the regents' meeting room while they were in recess. The regents moved to another place and completed the meeting, said university spokesman Joseph Owsley.

Police have looked on during the demonstrations but made no arrests, Owsley said.

The protesters later met with Shapiro, three of the regents, and a university vice president for 1 1/2 hours. Shapiro also scheduled a meeting for Monday with the Black Action Movement III, one of the groups that orchestrated the sit-in.

''We will do whatever we can to rid the campus of that, whether it's black, white or any other antagonisms between people here on campus,'' Shapiro said.

Ransby said after the sit-in that the coalition would discuss its strategy next week and soon take other actions that ''would really make the university hurt.''

''It is clear now who and what we are up against,'' she said. ''We are here to build a movement. We are going to get stronger and stronger.''

Among the protesters' demands were an increase in black enrollment, establishment of an office of minority affairs, a mandatory workshop on racism for incoming students, and a required course on bigotry.

The protests followed several racial incidents at the university, including the airing of anti-black jokes on a campus radio station and threats against black dormitory residents. The incidents triggered a state House hearing at the campus.

Thursday's sit-in came 17 years to the day after black students calling themselves the Black Action Movement began a strike that shut down the university. One of their demands, agreed to by the administration, called for 10 percent black enrollment.

That goal was never met. Black enrollment stood at 5.3 percent last fall, with overall minority enrollment at 12.7 percent.