Seamus Roberston and his Vietnamese wife-to-be Pham Thu Thuong Nguyen are disappointed they'll be getting married without Thuong's family there.

A Vietnamese woman will walk down the aisle alone after her family were declined visitor visas to New Zealand in a move labelled "nasty and vindictive" by her husband-to-be.

Pham​ Thu Thuong​ Nguyen, known as Thuong, and her fiance, Kirk Robertson, known as Seamus, are getting married on Saturday at the Sacred Heart Catholic Church in Oxford, North Canterbury.

But her mother, two sisters, brother-in-law and niece will not be able to make the ceremony after Immigration New Zealand (INZ) declined their visa applications on the grounds they had limited incentives to return to Vietnam.

JOSEPH JOHNSON/STUFF A photo album from the Thuong and Seamus' engagement party in Vietnam.

"She was distraught after hearing her family wouldn't be coming," Robertson said, speaking from his family home where he and Thuong have been living since December.

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"It's the only day in her life she's ever going to get married and because of some bureaucratic glitch they are disallowing her the opportunity to have her family here for her wedding. That is cruel and vindictive."

JOSEPH JOHNSON/STUFF Angus Robertson says he feels "wild" after INZ declined visitor visas for his future daughter-in-law's family.

The couple have had their issues with INZ. In September, the department gave Thuong 42 days to leave the country after declining her application for a year-long Partner of a New Zealander Work Visa.

The visa was declined by INZ because it was not satisfied Robertson and Thuong were living together in a genuine and stable relationship, despite more than 100 pages of submissions in support from friends and family.

The couple started a relationship in 2016 and had been living together since December after Robertson moved back from Australia to look after his terminally ill father and the family business after the death of his mother.

Because they were staying with his 77-year-old father, Angus Robertson, Seamus Robertson said they had no rental agreement or utilities bills to help prove they lived together.

"The irony is 100 years ago [this week] my grandfather stood on the fields of Passchendaele and fought for New Zealand's freedom, and now some immigration official is saying his grandson is not trustworthy," he said.

Robertson was convinced INZ had declined visas for Thuong's family because of her own visa situation.

DAVID WALKER/Stuff Seamus Robertson is in a battle with Immigration New Zealand after his Vietnamese partner, Pham Thu Thuong Nguyen, was denied a working visa.

"It's meant to be the happiest day of our lives and they're making sure that the spectre of deportation looms over her head."

INZ area manager Sarah Clifford said while Thuong's immigration status was considered during the assessment of her family's visa applications, it did not play a significant factor.

Their visas were declined on "bona-fide grounds due to limited incentives to return home", she said.

JOSEPH JOHNSON/STUFF A photo of Seamus Robertson's grandfather, Angus McIver, who fought in the World War I battle of Passchendaele.

"All five live in a high-risk area of Vietnam, have no previous travel history to any countries, declared low employment or self-employment in Vietnam and limited evidence of personal funds or savings."

Angus Robertson said the decision was insulting.

He personally sponsored each of Thuong's relatives' visa applications, which included a guarantee he would cover any enforcement costs should they not meet their visa requirements.

DAVID WALKER/STUFF Pham​ Thu Thuong​ Nguyen and fiance Kirk 'Seamus' Robertson are getting married on Saturday in Oxford, Canterbury.

"What they're saying is they want me to be responsible, then they turn around and say 'we won't let these people in because we think they're gong to stay and work, which means you Mr Robertson are crap'," he said.

"They won't bloody stay, they want to come for the wedding then go home."

The 77-year-old had also offered to pay for all their costs during the trip to New Zealand, a repayment of sorts after the engagement party Thuong's family had put on in Vietnam in April.

"I'm a taxpayer, I pay my taxes, they're public servants who are supposed to do their job properly and they haven't done it. So that just made me wild," he said.

Seamus Robertson and Thuong had applied for ministerial intervention in her case, and the couple were also appealing the decision through the Ombudsman.

Clifford said the ministerial intervention request would be considered by a senior INZ official.

"INZ can confirm that no compliance action will take place until the request has been decided," she said.