Wellington - The U.S. Navy plans to send a ship to New Zealand in November, Prime Minister John Key said on Thursday, formally ending a standoff over the Pacific nation's anti-nuclear policy that dates back more than 30 years.

If the ship meets New Zealand's legal requirements it will attend the Royal New Zealand Navy's 75th anniversary, Key said, a day after U.S. Vice President Joe Biden assured neighbor Australia there would be no retreat from Washington's pivot to the Asia-Pacific region regardless of who wins November's presidential election.

"Vice President Joe Biden confirmed in our discussions today that the U.S. has accepted the invitation and intends to have a ship represent the U.S. Navy at this event," Key said during Biden's one-day visit to New Zealand.

Biden said it was "another expression of our close and cooperative relationship".

Under New Zealand law the prime minister can only grant approval if he is satisfied "that the warships will not be carrying any nuclear explosive device upon their entry into the internal waters of New Zealand".

Biden did not offer any detail about which ship would be attending.

It will be the first visit by a U.S. warship in more than three decades. In the mid-1980s, the Labour government of the time announced its decision to ban ships that were either nuclear-powered or nuclear-armed.

The United States would not confirm or deny whether its ships had nuclear capacity leading to a stalemate between the two nations.

The United States and Australia viewed the move as a breach of the three-way ANZUS treaty, which dates back to 1951. In 1986 it suspended treaty obligations to New Zealand.

Despite the rift, the nations have remained close allies.  New Zealand supported the U.S.-led war on terror in Afghanistan and has sent soldiers to help train Iraq's armed forces.

Key told local press that the ship must meet the legal requirements.

"There is a long-standing process for considering ship visits under our nuclear-free legislation," Key said. "I will receive advice in due course to assist me in making a decision."