CAEN, France (AFP) - US President Barack Obama said Saturday it was vital to break the "stalemate" in the Middle East peace process, saying all sides had to recognise that their fate was inextricably linked.

"We have to move beyond the current stalemate," Obama said at a press conference in France where he was to attend commemorations marking the 65th anniversary of D-Day.

"Progress would mean the parties involved, supported by not just the United States, not just by France but by other Arab states, are making serious constructive steps towards a two-state solution," he said when asked what he wanted to see by the end of the year.

"I do not expect that a 60-year problem is solved overnight, but as I said before I do expect both sides to recognise that their fates are tied together and that it is in the interests of Israel, in its security interests, and in the interests of the Palestinians to resolve this in a peaceful way." Obama, who has called on Israel to halt all its settlement activity in the occupied West Bank, said he wanted Arab nations to all be part of the peace process.

"The Arab states have to be a part of this process," said the US president.

"They are going to have to step up as well because Arab states are not only important politically but are important economically." His comments came ahead of a visit to the region by his special envoy, former US senator George Mitchell.

"We are going to try to put as much energy as we can into it," said Obama.

Internal feud

Hamas movement on Saturday protested the killing of its fighters by Palestinian police in the West Bank as its own Gaza-based security forces launched a new campaign of arrests.

Around 2,000 women Hamas supporters protested against Palestinian President Mahmoud Abbas after nine people were killed in violent clashes between his police and Hamas fighters in the Israeli-occupied West Bank this week.

"No to Abbas, No to Fayyad," the women in Gaza City chanted, referring to his Western-backed Prime Minister Salam Fayyad, who has launched a security crackdown across the territory over the past several months.

The women waved green Hamas flags and held signs reading "Abbas' security forces are the bodyguards of the Zionists" and "No dialogue with arrests in the West Bank". Two Hamas members and a Palestinian policeman were killed in a shootout on Thursday in the West Bank town of Qalqiliya, and six people were killed in a similar gunbattle there earlier in the week.

An investigation by Al Haq human rights organisation published on Thursday said Hamas fighters opened fire first on both occasions.

But senior Hamas leader Ahmed Bahar accused Abbas and Fayyad of treason for allegedly cooperating with Israel against the Islamist movement.

"You can either return to the Palestinian people and the dialogue in Cairo or you can continue your treachery in the embrace of the [Israeli] occupation," he told the crowd of protesters.

"But this occupation will never do anything for you. They will toss you aside as they have tossed aside others in the past." Meanwhile, officials in Abbas' Fateh Party in Gaza and the West Bank accused Hamas-run security forces of detaining scores of its members in a campaign of arrests launched overnight.

"In Gaza, the arrests and abductions against us continue," said Fahmi Al Zaarir, a Fateh spokesman in the West Bank. "There are more than several dozen people wanted by Hamas and they began arresting them last night." The Hamas-run interior ministry in Gaza said it was targeting "criminal and outlaw groups" accused of collecting information on its leaders and hideouts to sell to Abbas' Palestinian Authority and Israel.

The bitter divide between the two groups climaxed in June 2007 when Hamas gunmen drove Abbas' forces from the Gaza Strip in a week of deadly street battles that cleaved Palestinians into hostile rival entities.

Since then each movement has accused its rival of political arrests and persecution in the territories under its control.

The two sides have held several rounds of negotiations in Cairo this year aimed at resolving their differences and forming a national unity government, but without visible progress.

A senior Fateh official said a delegation would travel to Cairo later on Saturday for talks with Egyptian officials aimed at "containing the events in Qalqiliya and the escalation of arrests by Hamas". The delegation would not meet with any Hamas official during the trip.

In southern Gaza, a 21-year-old Palestinian was killed by an explosion which witnesses said was caused by unexploded munition near his house east of the town of Khan Younis.

In a separate incident, a 22-year-old Palestinian was moderately wounded when Israeli warships fired shots at fishing boats near the southern Gaza town of Rafah, according to Palestinian medics and witnesses.

The Israeli military said the navy fired warning shots at the fishing boats after they crossed into a closed military area but that no one was wounded.