LONDON, Dec 30 (Reuters) - A British ambassador to Israel warned as early as 1980 that Israel would detonate a nuclear bomb in case of a new war with the Arabs, according to previously secret state documents released on Thursday.

If they (Israelis) are to be destroyed, they will go down fighting this time. They will be ready to use their atomic weapon, ambassador John Robinson wrote in a cable to the Foreign Office on May 4, 1980.

Israel has never confirmed or denied having atom bombs under a policy of ambiguity to deter numerically superior foes.

Robinson's message, published under a rule that allows official British papers to be released after 30 years, voiced concern that U.S.-hosted negotiations would not lead to a comprehensive agreement on the Middle East conflict.

As long as there is no agreement on the West Bank and Jerusalem which satisfies the Palestinians, they will be driven increasingly to extremism; moderate governments in the area and Western interest will be increasingly threatened; opportunities for Soviet influence and intervention will increase; and so will the danger of a new war, the cable said. (Reporting by Olesya Dmitracova, editing by Mark Trevelyan)