A Middle East treaty creating a Palestinian state at peace with Israel can be completed in one year of negotiations, say major powers who were due on Friday to invite both parties to start talks in two weeks.

The Quartet -- the United States, European Union, Russia and United Nations -- were due to issue a statement later on Friday confirming that President Barack Obama would invite the Palestinian and Israel leaders to Washington on Sept 2.

A copy of the statement seen by Reuters reaffirms their strong support for direct negotiations to resolve all final status issues and end the 62-year-old conflict.

It reaffirms the Quartet's "full commitment to its previous statements" made in the past year calling for a settlement "that ends the occupation which began in 1967 and results in the emergence of an independent, democratic, and viable Palestinian state living side by side in peace and security with Israel and its other neighbours".

The statement does not refer explicitly to the Quartet's repeated calls on Israel to halt all settlement of occupied territory in the West Bank where the Palestinian state would be established.

"The Quartet expresses its determination to support the parties throughout the negotiations, which can be completed within one year, and the implementation of an agreement," it says.

It also urges both sides to refrain from provocative actions and inflammatory rhetoric.