Two Palestinian politicians have been stopped from canvassing in east Jerusalem by Israeli police, at the start of the Palestinian poll campaign.
Israel says Palestinian political activity in east Jerusalem is illegal
The candidates were told no Palestinian political activity was allowed in the area, under Israeli law.
Palestinian leader Mahmoud Abbas says he will postpone the vote planned for 25 January if Israel refuses to allow Palestinians in the area to take part.
His ruling Fatah party launched its campaign at Yasser Arafat's grave.
Rival Islamic militant group Hamas is making a strong challenge in the first general election in 10 years.
Correspondents say the election is seen as a major test for Fatah, which is regarded as corrupt and ineffective by large numbers of Palestinians.
Israeli police stopped Hanan Ashrawi, from the Third Way party, and Mustafa Barghouti, standing as an independent, from canvassing on the first day of campaigning.
Ms Ashrawi told the BBC she was carrying election posters when officers arrived and told her it was illegal for her to campaign in the area.
She was allowed to leave but one of her assistants was detained.
A spokesman for the Jerusalem police said Israeli law stated no Palestinian political activity was allowed in east Jerusalem, occupied by Israel since 1967.
But it is still unclear if Israel will carry out its threat to ban Palestinians from voting in east Jerusalem in protest at the participation of candidates from Hamas.
Mr Abbas said all Palestinian factions agreed there could be no election if such a ban goes ahead, but Hamas rejects delaying the poll.
"We have told them [Fatah] that postponing the election will lead to a vacuum and to a dark future," leading Hamas candidate Ismail Haniya told a rally in Gaza City.
Fatah has governed the Palestinians since the first and only parliamentary elections in 1996.
The party opened its election campaign at the late Palestinian leader's tomb in Ramallah in the West Bank.
With Mr Abbas on a tour of the Gulf states, Fatah campaign manager Nabil Shaath delivered the keynote speech to supporters and candidates.
"We will fight to finish the occupation and the wall [Israel's West Bank barrier] and the settlements and establish a Palestinian state in a peaceful resolution to the situation in our region," he said.
Fatah also had a "programme to stop the corruption and establish the new foundations for a Palestinian state", he added.
Hamas launched its campaign in Gaza City outside the home of its former leader Sheikh Ahmed Yassin, who was assassinated by Israel nearly two years ago.
Polls suggest Hamas could win up to a third of the vote.