A BNR reporter who was covering the inauguration said that when the power went off the gondolas slid slowly backward, colliding with each other.
An emergency power generator was switched on, allowing the cabins to return slowly to their starting point, where Stanishev and the other officials stepped out of the cabins, BNR said.
"The prime minister was very calm during the whole accident," local Mayor Kostadin Paskalev, who was in the same cabin with Prime Minister Sergei Stanishev, told reporters.
An official at Stanishev's office declined to comment.
The accident occurred at the new Kartala resort, 100 kilometers (60 miles) south of the capital, Sofia, and the cause of the possible power failure was not immediately known.
Environmentalists had staged protests against construction of the ski resort, arguing that it was causing irreparable damage to forests and wildlife on Mount Rila.
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