Zimbabwe ? Opponents of President Robert Mugabe accused his regime Tuesday of unleashing thugs to attack opposition supporters and seizing white-owned farms in an attempt to retain power. They called on other African powers to intervene.

Mugabe, who has led Zimbabwe for 28 years, has virtually conceded that he did not win March 29 elections and appeared to be campaigning for an expected runoff against Morgan Tsvangirai by intimidating foes and fanning racial tensions.

Election results remained secret, and a High Court judge heard an urgent opposition petition Tuesday to force their publication. The hearing resumes today.

Information Minister Sikhanyiso Ndlovu denied the accusations of violence.