Israeli forces launched multiple arrest raids overnight Monday against Hamas affiliates in the West Bank, Hamas sources and locals said.

Hamas leader Rafat Jamil Nasif, 45, was detained in Tulkarem in an arrest raid on his home, sources in the Islamist movement said. Nasif's family were forced to stand outside in the cold while sniffer dogs searched his home.

Musab al-Ashqar, Abdullah Ismail al-Khalil and Ammar Jihad Ameir, students at al-Khadouri university, were also arrested in Tulkarem, together with the local Imam's son Qitad Amar Bidawi.

In Nablus, Israeli forces detained a local Islamist student leader Muthanna Jamil Eshtayeh and students Osama Khalid Yamin and Walid Jamal Asida from An-Najah university, locals said.

Mousa Ahmad Yamin and Abed al-Ghani Ayesh Samara were also detained in nearby villages.

Four people were arrested in Qalandia refugee camp in Ramallah, including two ex-prisoners, and in Hebron two other students were detained.

An Israeli army spokeswoman said that 13 people were detained overnight, including four in Nablus, five in Tulkarem, three in Bethlehem and one in Hebron.

Another military spokesman said nine people arrested were affiliated with Hamas.

The latest detentions follow a sweep of arrests of Hamas-affiliated officials in the West Bank over the past week.

Last Tuesday, Israeli forces arrested 12 people including at least three Hamas-affiliates.

A day earlier, Israeli soldiers arrested 23 members of Hamas, including three lawmakers -- Ahmed Attoun in al-Bireh, Hatem Qafisha in Hebron and Mohammed al-Tal in al-Dhahiriyya.

Hamas condemned the arrests as a "criminal act."