Hamas has arrested and tortured dozens of Palestinians in the Gaza Strip over the past few weeks on political grounds, a Palestinian rights group said Wednesday.

The Gaza-based Palestinian Center for Human Rights condemned the "arrest campaign launched by the Internal Security Service (of Hamas) against dozens of persons, including members of (the) Fatah (party) and children."

It said arrests had been stepped up to coincide with calls for demonstrations against Hamas on the anniversary of the death of Palestinian leader Yasser Arafat.

The protests were called by the Tamarrod movement, which is inspired by the Egyptian group of the same name that organised the mass protests attending the army's ouster of president Mohammed Morsi.

Morsi hails from the Muslim Brotherhood, an organisation with branches across the Middle East whose Palestinian affiliate is Hamas.

Detainees told PCHR "that they were subject to torture, including being hit on hands and feet by a stick, punched all over their bodies, shackled, and forced to stand for long hours."

Others were "forced to sign oaths to abide by (the) law, not to assemble for participation in demonstrations, not to be in areas of friction with the police, and not to incite people against the government," the PCHR said.