Thousands of Palestinians took to the streets of West Bank cities Monday in support of president Mahmud Abbas's visit to Washington for talks with Barack Obama about the peace process with Israel.

Demonstrators waved the Palestinian national flag as well as that of Abbas's Fatah party, chanting "we are with you, president!" as Abbas was to weigh up an anticipated US request to extend the faltering negotiations with Israel.

"We're here today to stand up to pressures upon us and make sure president Abbas adheres to his convictions," said Nasser Eddin al-Shaer -- former Palestinian education minister and member of Fatah's Islamist rivals Hamas -- who joined a 5,000-strong rally in the northern West Bank city of Nablus.

Some 1,500 people turned out in the West Bank administrative centre of Ramallah, and more than 1,000 in the southern flashpoint city of Hebron.

Abbas was to meet President Obama in Washington on Monday, having travelled to the US nearly a fortnight after Israel's Prime Minister Benjamin Netanyahu did the same, and as an April 29 deadline for the nine-month negotiations loomed.

Palestinian and Israeli leaders have been unable to move the talks forward since US Secretary of State John Kerry kick-started them at the end of July after intense efforts to bring the sides back to the table following a three-year freeze.

Bitter recriminations have taken precedent, with the two sides refusing to budge on key issues such as the borders of a future Palestinian state, security arrangements in the West Bank, the fate of Palestinian refugees and the final status of Jerusalem, claimed by both sides as a capital.

- 'Waiting for peace' -

Israeli President Shimon Peres sought to clear the air on Monday, issuing a statement of support for Abbas.

"President Abbas is a man of principle; he is against terror, against violence. He is a good partner and I'm glad that our government is negotiating with him," Peres's office quoted him as saying in a statement.

"We are all waiting for peace; it is the wish of the Israeli and Palestinian people."

The US is to propose a framework on which to base final status talks and has been calling for an extension of negotiations pending agreement by both sides on that framework.

Israel has recently kicked up a new obstacle to ending the decades-long conflict, demanding Palestinian recognition of it as a Jewish state.

Palestinian leaders have categorically rejected the calls.

In the Hamas-run Gaza Strip, public demonstrations were banned, but Fatah supporters nonetheless gathered at the Al-Aqsa University, a bastion of the West Bank-based movement.

"We informed Fatah members of the ban on celebrations they'd demanded to support Abu Mazen (Abbas), in order to maintain public order, and fearing that inter-Fatah differences could air themselves in public," said Islam Shahwan, a spokesman for the Hamas government.

Abbas has had a spat with an exiled Fatah leader Mohammed Dahlan, both accusing each other of complicity in the death of late Palestinian president Yasser Arafat.

Witnesses said there were confrontations between Fatah members at the 2,000-strong rally at Al-Aqsa University.