A court in the Kenyan coastal city of Mombasa has authorized police to detain three women for 30 days as detectives investigate allegations they tried to join the Somali Islamic extremist group al-Shabab.

Magistrate Diana Mochache said the women could be held while police carry out investigations. Court documents said when the three suspects were arrested Wednesday they possessed a laptop, mobile phones, military boots, surveillance equipment and other devices.

Kenya, which has a border with Somalia, has been attacked many times by al-Shabab, which opposes Kenya's military involvement in the Horn of Africa nation.

In April al-Shabab attacked a college campus in northeastern Kenya, killing at least 148 people.