SOFIA, BULGARIA, JUNE 13 -- Protests by Bulgarian students and anarchist groups paralyzed central Sofia today, reflecting public impatience at delays in the release of detailed, officials election results.

Hundreds of boisterous youths, many waving flags of anarchist organizations or banners of the opposition Union of Democratic Forces (UDF), blocked the capital's busiest traffic intersection with overturned trashcans and boards.

The barricades caused chaos in Sofia's side streets and many Bulgarians had to walk to work, while others stayed home. Police appealed for calm but did not try to dismantle the barricades.

Bulgaria's dissident-led opposition has been stunned by preliminary results showing the vote here to be the first of Eastern Europe's free elections to return the former Communist Party -- now the Socialists -- to power.

A statement from UDF headquarters said, "It is unacceptable to block traffic junctions and to organize noisy protests with cars at night. This turns public opinion against the UDF."

University students, holding a sit-in to demand an investigation into alleged voting malpractices, also dissociated themselves from the street protests outside their faculty building. Bulgarian radio reported sit-ins and similar other protests by young people in at least 12 other towns.

According to a batch of official results released today in the voting for a new 400-seat legislature, the Bulgarian Socialist Party won 75 out of 200 seats that represent local constituencies. The UDF won 32. Runoff elections will be held in 81 constituencies Sunday between candidates who failed to win clear majorities.

In the other 200 races, for seats representing regions, a poll has shown the Socialists leading the UDF. Results in those races are expected Wednesday.