Authorities rounded up thousands of young men in the wake of the blasts at Sinai resorts that killed more than 100 people.

Egypt blamed the attacks on Bedouin with extremist beliefs.

Between 40 and 50 women accompanied by their children gathered at the district office for North Sinai security, calling for their relatives to be released or given a fair trial, one of the protesters told Reuters.

Police put a security barrier around the women to prevent them from approaching the office and forbade local residents from taking part in the demonstration, the protester said.

An Egyptian security source told Reuters many of the Bedouin in custody were still being investigated.

"Most of those arrested are still undergoing investigation and have had their arrests renewed by the prosecution ... there are a number arrested for smuggling through the tunnels (into Gaza) and their investigations are ongoing," the source said.

The source did not give the number of Bedouin now held.

Egypt has an emergency law in place that allows detentions without charge for indefinite periods.

Relations between Bedouin and the police have long been strained. In February, Bedouin killed two policemen and freed suspects on their way to a court hearing.

In November, Bedouin injured 11 police who seized cement they were trying to smuggle to Gaza through tunnels.