Peta had reportedly been harassed by police
Basildon Peta, who is the local correspondent of the British newspaper, The Independent, had been held overnight in Harare central prison.
Mr Peta, who is also the secretary general of the Zimbabwean Union of Journalists, is the first journalist for the international media to be detained under the Public Order and Security Act, just days after it came into effect.
If convicted, he could have been sentenced to two years in jail, the newspaper said.
Restrictive laws
The Zimbabwean Government denied the law was designed to stifle opposition in the run-up to next month's presidential elections.
The law makes it a crime to criticise or ridicule President Robert Mugabe and prescribes the death penalty for acts of "insurgency, banditry, sabotage or terrorism".
Mr Peta was able to telephone his wife, Florence, before he was detained, the Independent reported.
"He told me he was fine and not to worry, but I think he is in low spirits," she told the newspaper.
The newspaper said Mr Peta had been regularly harassed by police over articles he wrote criticising the government.
It said before his arrest, police told Mr Peta they were acting on orders from the highest levels of government.
The newspaper said last year Mr Peta's name topped a security services hit list and that he and four other journalists were to be "killed or harmed" before the election.
He is Special Projects Editor of Harare's Financial Gazette and has frequently unearthed stories of government corruption.
EU threat eases
Responding to Mr Peta's arrest, Glenys Kinnock, a member of the European Parliament for the UK's ruling Labour Party, said: "I urge the authorities to release him and allow him and his colleagues to report freely."
The opposition Movement for Democratic Change is set to mount the strongest challenge to Mr Mugabe's leadership since he came to power in 1980, in elections on 9-10 March.
Mr Peta's detention came shortly after the European Union said there was no need to take a decision on sanctions against Zimbabwe, because it had not sought to prevent the deployment of a team of EU election observers.
European Union foreign ministers had formally warned Zimbabwe a week ago that their 15 nations would impose "targeted sanctions" on Mr Mugabe's regime unless it allowed EU observers into the country.