* U.S.-based professor called the mastermind
* 32 to present defence case on Aug 26
By Barry Malone
ADDIS ABABA, Aug 7 A U.S.-based university professor is among 13 men convicted in absentia by Ethiopia for plotting to overthrow the government, the state news agency said on Friday.
Berhanu Nega, who is Ethiopian-born with U.S. nationality and teaches economics at Philadelphia's Bucknell University, was accused of masterminding a plan to topple Prime Minister Meles Zenawi.
The Ethiopian News Agency said the Federal High Court had issued the guilty verdicts late on Thursday. Government officials did not immediately comment.
The 13 are mostly based in the United States and Britain. Another 32 men in Ethiopia -- mainly former and current army personnel, including two generals -- have been charged. Three have been bailed and 29 are in custody.
The prosecution has presented its case and the defence will begin on August 26, relatives told Reuters.
Addis Ababa says the group had planned to kill senior government ministers and blow up power and telecommunications facilities to provoke protesters who would then march on government buildings and try to topple the government.
The arrests have worried rights groups, who say the Ethiopian government has become increasingly authoritarian.
Berhanu has publicly said he wants to overthrow the government but calls the accusations baseless.
Opposition parties say the charges have been trumped up in order to round up opponents ahead of a national election due next year.
Security forces killed about 200 protesters after a poll in 2005 when the opposition disputed the government's victory.
Berhanu was elected mayor of the capital Addis Ababa in that ballot, but was arrested along with other opposition leaders and accused of orchestrating the street protests.
He was pardoned in 2007 and went to the United States, where he set up his "May 15" opposition group, named after the date of the 2005 election. (Editing by Daniel Wallis)