GAZA, Oct 9 (Reuters) - Hamas and Fatah committed "grave breaches" of international law in their brief civil war in the Gaza Strip in June, a Palestinian human rights group said on Tuesday, detailing a series of extra-judicial killings.

In a new report, the Palestinian Center for Human Rights (PCHR) said 161 Palestinians, of whom 41 were civilians, were killed during fighting between June 7 and June 14 in which Hamas Islamists took control of the territory from secular Fatah.

"The two sides perpetrated grave breaches of the provisions of international law concerning internal armed conflicts, including extra-judicial and wilful killings and shooting at combatants and civilians after capturing them," the PCHR said.

In some cases, people were seized by gunmen in their homes and their bodies were later found dumped in remote areas.

"The PCHR also documented a number of cases, in which militants executed wounded persons during their evacuation to hospitals," the 105-page report said, citing testimony from relatives of the dead.

At least two people -- a Fatah fighter and a Hamas member -- were pushed to their deaths from tall buildings, said the PCHR, the leading Palestinian human rights group in the Gaza Strip...

Egypt confirmed on Tuesday that 30 Islamic Jihad operatives have entered the Gaza Strip through the Rafah crossing, Palestinian news agency Ma'an reported.

According to the report, most of those who returned to Gaza are terrorists belonging to the Al Quds Brigades, the military wing of the group.

The operatives were injured during the Intifada and were abroad for medical treatment.

Official sources of the brigades denied the reports, although the Islamic Jihad confirmed that one man did return to Gaza with full cooperation of the Egyptians.

Last week, Egypt allowed 80 more Hamas operatives to return to Gaza.