The United States has lifted a ban that prevented New Zealand naval ships visiting American ports or bases.

The ban had been in place since the 1980s, and US defence secretary Leon Panetta says the policy change will begin a "new era" in relations.

"I suspect that soon we'll be able to see one of those ships in our ports," he said in Auckland.

Speaking during a joint news conference with his New Zealand counterpart Jonathan Coleman, the Pentagon chief also announced that restrictions on meetings between defence officials and military exercises had also been rescinded.

"These changes I think are important and are in the interests of both our nations," he said.

The announcement underscored improving security ties between the two countries since a chill during the Cold War, when New Zealand imposed a ban on any visits by US nuclear-armed or nuclear-powered ships to its ports.

"While we acknowledge that our countries continue to have differences of opinion in some limited areas, today we have affirmed that we are embarking on a new course that will not let these differences stand in the way of greater engagement on security issues," Mr Panetta said.

Mr Coleman has ruled out any change to New Zealand's policy on barring nuclear armed ships but says the two nations have "moved past" that issue.

The Australia, New Zealand, United States Security (ANZUS) treaty was suspended between Wellington and Washington in 1986, but in recent years both sides worked to enable closer military cooperation without restoring the provisions of the treaty.

Mr Panetta's trip to New Zealand was the first by a Pentagon chief in 30 years and the first since the ANZUS treaty terms were suspended between the two countries.

AFP