WELLINGTON -- A three-way trade and economic agreement spanning major cities in southern China, the United States and New Zealand is already mulling proposals for city-to- city collaboration, the mayor of New Zealand's biggest city said Monday.

The Tripartite Economic Alliance between Auckland, Guangzhou and Los Angeles, which was signed Sunday in Guangzhou, was the centerpiece of celebrations to mark the 25th anniversary of Auckland's sister city relationship with Guangzhou, said Auckland Mayor Len Brown.

"Auckland with two influential Pacific Rim city economies will both raise our global profile and create new economic opportunities for Auckland businesses," he said.

"Guangzhou and Los Angeles are Auckland's most well-established and economically important sister cities," Brown said in a statement from his office.

A Tripartite Project Team was working on forging connections between the cities' education, screen and digital, innovation, as well as tourism sectors to identify opportunities as part.

The three cities were already considering a range of initial proposals, including working on air quality solutions, sustainability, waterfront regeneration, port-to-port alliance, chambers of commerce cooperation, film distribution, retail and fashion promotion.

The agreement, which would formalize a high-level political and strategic commitment, would initially be three years long, with an option to extend it if all the cities agreed.