Sheik Hassan Yousef, a Hamas founder and one of its leaders, was arrested late Wednesday and detained in a military facility near Nablus, Haartez reported.
Yousef was traveling with his wife and children at the time of his arrest, The Jerusalem Post reported. The reason for the arrest was not released.
Defense Minister Ehud Barak said Israeli forces are on high alert in the wake of a deadly attack 10 days ago on the Sinai border.
"Readiness is very high. We are determined to strike at those carrying out the attacks, to take action as much as possible to intercept the attack and we are reiterating that responsibility stems from the Gaza Strip. It is not just Islamic Jihad but also Hamas," Barak said.
The Hamas leader was released from prison last month, a month-and-a-half early from his 6 year sentence as a goodwill gesture by Israel for Ramadan.