Israel's new ultranationalist foreign minister said Prime Minister Benjamin Netanyahu's right-leaning government would not be bound by US-backed understandings on a Palestinian state reached in 2007.

Avigdor Lieberman's dismissal of the Annapolis conference declaration could swiftly steer Israel and Netanyahu onto a collision course with US President Barack Obama, who last week reaffirmed Washington's commitment to Palestinian statehood.

"It has no validity," Lieberman, an ultranationalist, said in an inaugural speech at the Foreign Ministry. He was referring to a joint declaration issued by Palestinian and the then Israeli leaders in November 2007 at Annapolis, in the US state of Maryland.