WASHINGTON, Sept 9 (Arshad Mohammed/Reuters) - The United States said on Friday it has begun talking to Israel and the Palestinians about how to deal with the aftermath of a Palestinian bid for full U.N. membership despite U.S. and Israeli opposition.

While disclosing the contingency planning, a State Department spokeswoman said Washington did not regard such a Palestinian push as a foregone conclusion, even though a Palestinian spokesman reiterated such plans on Thursday.

Two senior U.S. envoys, David Hale and Dennis Ross, met Israeli and Palestinian officials in the region this week but appeared to make no progress in dissuading the Palestinians from trying to upgrade their status at the United Nations.

The United States and Israel argue that issues such as Palestinian statehood should be decided by the two sides at the negotiating table rather than at the United Nations.

The Palestinians believe acquiring full U.N. membership now -- a virtual impossibility because it requires Security Council approval and the United States has said it will exercise its veto -- will improve their bargaining position in any future negotiation.

The trip was certainly useful in terms of working with both sides to think through how we can continue to try to avoid the situation in New York and, if we can't avoid it, how we can manage things so that after New York we can still stand a chance to get back to the table, State Department spokeswoman Victoria Nuland told reporters at her daily briefing.

Our priority is plan A, which is that we can get them back to the table, Nuland added. There is no escaping the fact that it is difficult.

There have been no direct negotiations between the two sides since they collapsed nearly a year ago because of a disagreement over Jewish settlement construction on land that the Palestinians want for their state.

'NON-MEMBER STATE'

Diplomats have said it is not clear what the Palestinians will do when the U.N. General Assembly opens on Sept. 19.

Rather than seeking full U.N. membership for a state in the West Bank and the Gaza Strip -- territories occupied by Israel in the 1967 Middle East war -- they could seek status as a non-member state, which would require a simple majority of the 193-nation assembly.

At the United Nations, Palestinian representative Riyad Mansour said on Friday there could be a formal announcement of the Palestinian course of action following an Arab League meeting in Cairo on Monday.

Mansour said he understood that becoming a non-member state would allow the Palestinians to join the International Criminal Court (ICC) -- a possibility that worries Israel, which fears they could seek to have Israeli military leaders prosecuted.

It would also give them access to U.N. agencies such as the World Health Organization and the cultural organization UNESCO, he said.

The requirement of these agencies and the ICC is to be a state -- not necessarily a member state of the United Nations. So if we become a non-member state in the U.N. system, then that would qualify us to join these agencies as a full member with full rights and privileges, Mansour said.

A bill introduced in the U.S. House of Representatives last week by a Republican congresswoman would cut off U.S. funding to any U.N. entity that upgrades Palestinian status. The bill is unlikely to pass the Democratic-run Senate, however. (Additional reporting by Patrick Worsnip at the United Nations; editing by Mohammad Zargham)