The judicial authorities in Iran have arrested at least half a dozen journalists and bloggers over the past few weeks, according to their acquaintances, opposition Web sites and rights groups. The moves appear to be part of a pre-emptive campaign of intimidation to thwart protests surrounding the parliamentary elections that are scheduled to be held in early March.

The arrests of the journalists and bloggers, including two prominent women whose blog posts are widely read in Iran, have not been reported by the official news media. Rights groups and people who know the detained journalists said the government apparently wanted word of the arrests to spread informally, to heighten the atmosphere of fear and paranoia.

It also was unclear what specific charges, if any, had been lodged against those who were arrested. None seem to have been politically active or to have published anything that might be considered seditious since the last major Iranian government crackdown on free expression in February 2011. At that time, the authorities arrested a large number of journalists as part of what turned out to be a successful effort to subvert any ambition by Iran’s largely silenced political opposition to celebrate the revolutions that were then sweeping Tunisia and Egypt.

The government “can’t come out publicly and name them or charge them with anything, because they can’t justify why they’re holding them,” said Hadi Ghaemi, executive director of the International Campaign for Human Rights in Iran, an advocacy group in New York that has researched the arrests, adding that the journalists and bloggers were “prominent enough that the news will get around quickly and intimidate others.”