TEHRAN: Iran has arrested 25 journalists and other staff at a newspaper owned by defeated presidential candidate Mir Hossein Mousavi, one of its editors said on Wednesday, as the hardline press launched a vitriolic attack on the one-time prime minister.

The arrests come after the newspaper Kalemeh Sabz (Green Word) was shut down by the authorities in the wake of the disputed election that returned President Mahmoud Ahmadinejad to power.

"Among those arrested on Monday were five or six administrative employees while the rest were journalists," Alireza Beheshti said. "The agents who came to the newspaper did not show a warrant."

He said five women among the detainees had been released on Tuesday.

Kalemeh Sabz was only launched in the run-up to June 12 election by Mousavi, a former post-revolution premier who has alleged widespread fraud in the poll.

Scores of journalists and reformists politicians have been jailed following Ahmadinejad's re-election which triggered a week of mass protests and violent clashes between Mousavi supporters and security forces.

Iran has accused foreign media of provoking the protests, where at least 17 people have been killed, and has arrested at least two reporters working for US media outlets.

The country's intelligence police said they had found "evidence of a plot against national security" during an inspection of a presidential candidate's campaign office, without disclosing the identity.

"Documents on ties with dissident media, interference of foreigners and recent plots were discovered in this building," the official news agency IRNA said quoting a police statement.

"This place was in fact the headquarters for psychological warfare against security," it said. "The plotters were arrested and are being interrogated."

Hardline newspapers also launched a vitriolic attack on Mousavi on Wednesday, accusing him of being behind the bloody unrest that has rocked Iran since the vote.

"Who is responsible for the week-long crime in Tehran?" charged pro-Ahmadinejad newspaper Vatan Emrouz above a front-page picture of Mousavi.