US President George Bush has said he will cut aid to the Palestinian government unless Hamas abolishes the militant wing of its party and stops calling for the destruction of Israel.
In a television interview with America's CBS Evening News on Friday, Bush took a hard-line stance against the Hamas party, which swept Palestinian elections on Wednesday.
Earlier, the US State Department said all aid programmes to the Palestinians would be "reviewed".
Hamas, which has carried out scores of bomb attacks against Israeli targets, is classified by the United States as a terrorist group.
In addition to the threat of aid cuts, clashes between rival groups have added to the problems facing the Palestinian territories after Hamas' victory in Wednesday's election.
As dusk fell over the Gaza Strip on Friday, thousands of Fatah supporters flooded the streets, demonstrating outside the parliament building in Gaza City to call for the resignation of Palestinian President Mahmoud Abbas and the rest of the Fatah party leadership.
In the southern Gaza Strip, violence involving Hamas and Fatah supporters in Khan Yunus and other nearby towns also highlighted lingering tensions.
Clashes there left at least nine people wounded, including five members of the security forces.
Quartet meeting
International assistance will be a main topic when US Secretary of State Condoleezza Rice meets in London on Monday with foreign ministers from the European Union, Russia and the United Nations.
The four, known as the diplomatic "quartet", have been the main figures pushing the so-called "road map" to Middle East peace.
Legitimacy price
Despite being behind the majority of attacks on Israeli targets during a five-year Palestinian uprising, Hamas has carried out no bombings for more than a year.
The diplomatic "quartet" urged Hamas not only to renounce violence but also to accept Israel's right to exist.
PHOTO CAPTION
Fatah supporters burn Hamas flag and posters during a protest in Khan Younis, south of the Gaza City, January 27, 2006. (REUTERS)