WASHINGTON (Reuters) - U.S. Vice President Joe Biden on Monday acknowledged "overwhelming frustration" with the Israeli government and said the systemic expansion of Jewish settlements was moving Israel toward a dangerous "one-state reality" and in the wrong direction.

Addressing the J Street lobby group in Washington, Biden said despite disagreements with Israel over settlements or the Iran nuclear deal, the United States had an obligation to push Israel toward a two-state solution to end the conflict between Israelis and Palestinians.

"We have an overwhelming obligation, notwithstanding our sometimes overwhelming frustration with the Israeli government, to push them as hard as we can toward what they know in their gut is the only ultimate solution, a two-state solution, while at the same time be an absolute guarantor of their security," Biden said.

A two-state solution envisages a Palestinian state on most of the West Bank and Gaza Strip, lands Israel captured in a 1967 war, and an Israeli state that absorbs some of the settlements Israel built on occupied land in return for mutually agreed land swaps.

Biden said his recent meetings with Israeli Prime Minister Benjamin Netanyahu and Palestinian President Mahmoud Abbas left him discouraged over the prospects for peace at present.

"There is at the moment no political will that I observed among Israelis or Palestinians to move forward with serious negotiations," Biden said, "The trust that is necessary to take risks for peace is fractured on both sides."

He said both Palestinians and Israelis needed to tamp down rhetoric that fueled violence and actions that undermined confidence in negotiations.

Efforts by the Palestinian Authority to join the international criminal court were "only damaging moves that take us further from the path to peace," he said.

For Israel's part, Biden said the "steady, systematic expansion" of Jewish settlements on occupied land wanted by the Palestinians moved "Israel in the wrong direction."

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"They are moving toward a one-state reality and that reality is dangerous," Biden said, warning that moving in that direction would mean an endless cycle of conflict and retribution.

Biden condemned the bombing of a bus and attack on another in Jerusalem on Monday by "misguided cowards" and offered prayers to the injured and their families.

(This story has been corrected in paragraph 5 to show Netanyahu is Israel's prime minister, not president)

(Reporting by Lesley Wroughton; Editing by Richard Borsuk)