The United States and New Zealand signed an agreement to expand defense cooperation Tuesday but the deal does not alter Auckland's longstanding ban on port visits by nuclear-armed American warships, officials said.

The accord was the latest in a series marking US attempts to shift its strategic focus to the Asia-Pacific, as Washington keeps a wary eye on China's rising power.

New Zealand's Defense Minister Jonathan Coleman said the accord called for a security dialogue as well as joint exercises and other collaborative efforts between the two countries' armed forces.

"This high-level arrangement recognizes the significant security cooperation that exists between New Zealand and the US within the context of our independent foreign policy, and seeks to build upon that cooperation in the years ahead," Coleman said in a statement.

The Pentagon said the partnership "will include security cooperation in areas such as maritime security cooperation, humanitarian assistance and disaster relief, and peacekeeping support operations."

The agreement calls for bolstering "maritime domain awareness," a phrase that usually refers to the sharing of intelligence in monitoring naval traffic.

Senior US officials have forged similar agreements with other countries in the region, including Australia, in a bid to counter China's growing military and economic might.

Tuesday's deal illustrated a thawing of once chilly military relations between the two countries.

Since 1985, New Zealand has refused to allow American nuclear-armed and nuclear-powered ships to dock at its ports.

As Washington declines to reveal whether its ships are nuclear-powered or not, New Zealand has banned entry to all American naval vessels.

A Pentagon spokeswoman said the agreement had not altered the disagreement that dates back to the Cold War era.

"As for the port visits, while we value our strong partnership, our policies regarding nuclear ships do not fall in line and remain unchanged as a result of this declaration," Major Catherine Wilkinson told AFP.

"US Navy and Coast Guard ships will not port into New Zealand, but we look forward to other opportunities to engage with New Zealand Defence Forces," she said.