The United States is publicly calling for "comprehensive dialogue" with New Zealand to repair a relationship it implies has lacked trust and respect since the rift over anti-nuclear legislation in the mid-80s.

The call was made in a hard-hitting speech in Wellington last night by departing United States ambassador Charles Swindells - though he did not use the word "nuclear" once.

The speech painted the political relationship in far worse repair than the New Zealand Government portrays it. It suggested the US was deeply frustrated with the relationship and wanted to confront it through dialogue.

The speech hinted that the US might be willing to keep an open mind as to whether New Zealand's nuclear position would remain the impediment to improvement that it has been. Mr Swindells said that in an attempt to preserve the friendship between the countries, they had glossed over differences, worked "around the edges" and there had been "stifled dialogue".

A lack of dialogue created mistrust, Mr Swindells said.

Successive Governments had been "unwilling or unable" to deal comprehensively with the strains that had accumulated since the mid-80s - when New Zealand banned nuclear weapons and nuclear-propelled ships.

In what might be seen as a willingness to take a more relaxed attitude to the nuclear stand, Mr Swindells made a case for establishing a new level of relationship, even if the nuclear issue were not resolved in the talks. The US and New Zealand needed to talk "fully and openly" about what kind of relationship made sense. "Even if the discussion does not resolve the differences that we have, it would surely go a long way to help re-establish the trust that eroded 20 years ago."

He said he had not been prepared for a growing appetite by many New Zealanders "to rejuvenate the relationship by reviewing - or at the very least, discussing - the issues that divide us."

He suggested that if New Zealand was not willing to open up a new dialogue with the United States, it could be seen as increasingly irrelevant.

The status quo was not an option. "If you don't take decisive action, you may unintentionally end up in a place not to your liking."

Mr Swindells said "comprehensive dialogue" had led the US to a transition in its relationship with its previous enemy Vietnam.

Prime Minister Helen Clark said New Zealand was more than happy to have a dialogue with the US. But it saw the way ahead in terms of how other nuclear powers, Britain and France, had faced the situation: both countries continued to have ship visits to New Zealand.

"The way forward is the way that Britain and France took from quite an early point ... Any request for a United States warship to visit New Zealand would almost certainly be accepted."

Foreign Minister Phil Goff was at the function, to mark American Independence Day. He said the call to step up the relationship followed a discussion he had had with Mr Swindells several weeks ago.

"I very much hope that what he is saying is that the Administration wants to leave behind the negative side of the differences from the past, without expecting New Zealand simply to be a reflection of the United States policy in every respect."

The law

The New Zealand Nuclear Free Zone, Disarmament, and Arms Control Act, 1987 bans nuclear weapons and nuclear-powered ships from entering New Zealand's territorial waters.

The Prime Minister may grant approval to foreign warships if she is satisfied they are not carrying nuclear weapons.