Small but proud and highly educated cities, ranked among the most liveable in the world. Both with a love of rugby, the arts and culture, and each perched on the edge of wonderful natural beauty.

Now, Wellington and Canberra have been brought even closer together, with the Legislative Assembly soon to approve that the two become sister cities.

Chief Minister Andrew Barr will seek the agreement of the Legislative Assembly to establish the sister city arrangement on Thursday, after the Wellington City Council gave its in-principle agreement last month.

The announcement comes ahead of the start of international flights in September, which will offer a direct route to Wellington with Singapore Airlines.

That is expected to foster increased tourism and trade between the two capitals, something Mr Barr is seeking to capitalise on through a formal sister city relationship.

"Already we are witnessing the strengthening of ties between the two cities," he said. "We have agreed to potential areas for co-operation between our two cities, including business partnerships, tourism, education, cultural exchanges with national institutions, capital civic programs, biodiversity initiatives, smart city technologies, affordable housing solutions and sport."

Mr Barr is travelling to Wellington in July, and intends to formalise the sister city arrangement during that delegation.

Wellington Mayor Celia Wade-Broen visited Canberra for two days in April.

In an opinion piece last year, Mr Barr said Canberra would be a "natural destination" for New Zealand tourists.

"We share the Anzac legend and I would like the Australian War Memorial to become a must-visit destination for New Zealanders as it already is for Australians," he wrote.

"Our museums, our art, our culture, our food, our wine and the natural beauty of our surrounds are something I look forward to sharing with more New Zealanders."

Canberra already has a sister city arrangement with Nara in Japan, Beijing in China, and a "friendship city" agreement with Dili in Timor Leste.