Israel should join the nuclear Non-Proliferation Treaty (NPT), a pact intended to limit the spread of nuclear weapons, a top US official said Tuesday.

"Universal adherence to the NPT itself, including by India, Israel, Pakistan and North Korea...remains a fundamental objective of the United States," Assistant Secretary of State Rose Gottemoeller was quoted by Reuters as saying at a meeting of NPT signatories.

Gottemoeller would not say whether the US intended to press Israel to join the treaty.

Former prime minister Ariel Sharon's chief strategist, Dov Weisglass, said Gottemoeller's comments were very alarming.

"If these statements indicate a change in American policy on this issue, I believe this may be the most worrisome development for Israel's security in many years," he told Army Radio.