Opposition leaders in Ethiopia have accused the ruling party of killing and intimidating their supporters ahead of parliamentary polls on 15 May.
Meles Zenawi has been in power for the last 14 years
At least two opposition supporters had been shot and more than 40 jailed and tortured in the last month, they said.
Information Minister Bereket Simon rejected the allegations as "propaganda" and "absolutely false".
The National Elections Board said it would probe the complaints, although it had not been formally told about them.
But at the press conference five opposition groups - including the main CUD coalition - claim they had reported the matters and accused the electoral body of bias.
Prime Minister Meles Zenawi was re-elected in parliamentary elections in 2000, following Ethiopia's first multi-party elections in 1995.
The opposition say police are intimidating their supporters at campaign rallies and taking away their polling cards.
"As the election day approaches opposition parties are facing extreme difficulties such as random killings, imprisonment and disappearances," said the Oromo Federalist Democratic Movement party's Mesfin Nemera, AFP reports.
Mr Simon says the allegations are opposition campaign strategies.
"They are trying to tarnish the election process without reporting the incident to the authorities," he told the BBC.
The European Union is sending 150 monitors to observe the elections, but has said a decision to bar local observers is disappointing.
Some 25 million Ethiopians are able to vote for new members of parliament, who in turn choose a prime minister.
Some 35 parties are contesting the seats, although most of these are members of the three main coalitions: the ruling Ethiopian People's Revolutionary Democratic Front (EPRDF) and the opposition CUD and UEDF.
To date the elections have always been won by the EPRDF.