Ethiopian police locked down a university in the capital on Monday and arrested scores of students protesting election results they said were manipulated by the ruling party.

Police officers rounded up chanting protesters at Addis Ababa University, the scene of deadly riots in 2001, and took them away in four trucks.

The arrests were peaceful and there was no violence. Earlier, police had cordoned off the campus and chased away journalists.

Before the arrests, students behind the university’s locked gates could be seen shouting, singing and chanting against the results of the May 15 parliamentary elections.

"Those who have disrupted the smooth learning process and tried to instigate violence have been taken to the police station for questioning," Ethiopian Information Minister Bereket Simon said. He could not say how many had been arrested.

The protest came despite a month-long ban on public demonstrations imposed by the government after the polls.

Tensions have been rising in Africa’s top coffee grower since then, with the opposition accusing the ruling party of intimidation and vote rigging to stay in power.

"We shall struggle against the party which claims to have won the election when voters are declaring in clear terms they have not elected them," a leaflet passed out by the students said.

It accused the ruling party "of sowing the seeds of fear and suspicion among the Ethiopian people".

Preliminary results show the Ethiopian People’s Revolutionary Democratic Front (EPRDF), which has ruled for 14 years, and its allies have won enough seats to form the next government.

But the party’s majority was sharply reduced after the opposition made major gains in the elections, which were only the second real multi-party polls to be held in the country’s 3,000-year history.

The national electoral board, which is investigating voting irregularities, says final results will be ready on July 8.

Bereket called on the main opposition, the Coalition for Unity and Democracy (CUD), and other opposition parties "to stop instigating violence and abide by the democratic rules of the game".

CUD spokesman Bebebe Eshetu said it was not behind the protest.

"We approached the students by phone in an attempt to cool down the situation, but our call was rejected," he said.

More than 40 people were killed and 250 wounded at the university in April 2001 when police fired on rioters after students demonstrated for more academic and political freedom.

The opposition has accused Prime Minister Meles Zenawi’s EPRDF of threatening, harassing and jailing its candidates and supporters. It also filed a complaint against the electoral board, accusing it of bias in favour of the government.

New ballots were held in six disputed districts after allegations of fraud.