Israel has resumed its targeting of Islamic Jihad
The Palestinians were detained during two operations in villages close to Jenin and Nablus.
An M16 assault rifle was also discovered during the Jenin raid, an Israeli army spokeswoman said.
Israel is planning to remove four small Jewish settlements in the Jenin area as part of its disengagement plan.
The Israeli army has recently resumed its targeting of Islamic Jihad after a truce agreed in February broke down.
Under that agreement Islamic Jihad and fellow militants Hamas agreed to halt attacks on Israel in a deal brokered by Palestinian President Mahmoud Abbas.
But the truce had recently broken down with the Palestinians and Israel blaming each other for the resumption of violence in Gaza.
Islamic Jihad has claimed responsibility for two suicide bombings carried out in Israel during the truce.
The group recently said it would suspend attack rocket attacks on Israel during the disengagement from the Gaza Strip and the four small West Bank settlements.
Palestinian flag
During overnight raids, Israeli soldiers arrested 10 people, allegedly members of Islamic Jihad, a Palestinian militant group. The raids were conducted during two operations near the towns of Jenin and Nablus. An M-16 rifle was also discovered during the raid near Jenin.

Meanwhile, Hamas, a group friendly to Islamic Jihad, made a rare public appearance 2 days before the Israeli pull-out of settlers and troops from The Gaza Strip. They defied the Palestinian Authority by draping themselves in the colours of the group. On Friday, Palestinian Authority officials said only the Palestinian banner of red, black, green and white should be used to celebrate the withdrawal of Israel from Palestinian territory.

Hamas are planning to run in the parliamentary elections to be held in January, next year.