Egyptian security forces have arrested 12 members of the Muslim Brotherhood in the last two days, the latest in a series of arrests of members of the outlawed opposition Islamist group.

Seven Brotherhood members were arrested late on Friday and another five late on Thursday, security sources and the Brotherhood said on Saturday. At least 50 Brotherhood members have been arrested since March.

The Brotherhood’s web site said the five arrested on Thursday were all publishers who were planning to compete in their union’s elections next month.

Although the Brotherhood is outlawed, its members form the largest opposition bloc in parliament with nearly one fifth of the seats. They stand as independents to avoid the ban on their group.

The authorities occasionally crack down, arresting known Brotherhood members and holding them for belonging to an outlawed organisation.

The Brotherhood says the government is trying to rein it in after its success in parliamentary elections late last year.