Immigration New Zealand says it is working hard to improve processing times as it deals with a backlog of almost 12,000 people waiting to join their partners here.

Couples have told of their struggles to cope with long delays to be reunited, as they or their partners wait for visas, with some also facing separation from their children overseas.

Immigration New Zealand says those affected included New Zealand citizens and residents wanting their overseas partner to join them as well as work and student visa holders whose partners could apply to accompany them during their stay.

The agency's assistant general manager, Jeannie Melville, acknowledged there was a queue of 11,939 partnership temporary visas and says it was a result of increased numbers of people applying in all visa categories.

"We are working hard to address this issue and improve processing times," she says.

"INZ is currently recruiting for more staff who will be dedicated specifically to processing partnership applications."

Approving a visa was very complex and not a simple tick-box exercise, she added.

"INZ is regularly reviewing on-hand applications and prioritising low-risk, decision-ready applications to ensure these are processed as quickly as possible."

However, INZ will take longer to process applications where additional information or further checks are required.

"Temporary partnership visa applications are often a first step on a pathway towards applying for residence, and therefore they require careful consideration and verification of the evidence supplied."

Immigration figures suggest 95 percent of partnership visas are decided within four to seven months.

-RNZ/Gill Bonnett.