ASB fraudster Stephen Versalko gave an escort $10,000 for a clothes-shopping spree before taking her on a business trip to stay at a luxury hotel in Dubai - one of the smallest sums in the total of $2.55 million he paid her.

The ASB is suing the woman to recover some of the $17.8 million Versalko stole over nine years before he was discovered and jailed after a Serious Fraud Office investigation.

He spent most of the money on multimillion-dollar homes and a lavish lifestyle - including paying at least $3.4 million to two escorts and showering them with $800,000 of gifts.

Blue-chip properties Versalko owned in Remuera and Coromandel have been sold, with the $4 million from the sales being held in a trust account as the ASB attempts to claw back the stolen millions.

Court documents released to the Weekend Herald show the ASB is claiming $2.55 million from one of the women, who has name suppression, and connected companies.

The ASB is not pursuing the other escort, who received $791,181.85 from Versalko.

In the court file released by Justice Rhys Harrison, the ASB said it was "unconscionable" for Versalko to have made the fraudulent payments to the woman whom he met at the Pelican Club in Auckland.

The bank said it was also "unconscionable" for the woman - and companies she transferred funds into - to have kept the money.

The ASB statement of claim says that Versalko made two large payments to a company run by the woman: $1 million in December 2008 and $964,287 in April 2009.

The two sums were transferred directly from accounts of customers he defrauded

He made a further 19 payments to her between April 2008 and August 2009 of between $3500 and $100,000 shortly before the fraud was discovered.

Versalko also made several cash payments and gave her $10,000 to buy clothes to wear on a business trip to Dubai. The pair stayed at the exclusive Burj Al Arab Hotel, where the cheapest room costs US$2000 ($2980) a night.

Two other defendants in the ASB case are companies of which the woman is a director. She transferred $720,000 into one company to purchase a lifestyle block, where she now lives.

According to the ASB, a sum of at least $290,000 was transferred from the first company to the second company.

A fourth defendant is a property development company that received $520,000 from one of the companies owned by the woman.

Versalko met the 41-year-old at the Pelican Club, which charges clients $210 an hour or up to $1500 a night - although the women there earn considerably less than that.

Catherine Healy, of the New Zealand Prostitutes Collective, told the Herald in March that the escort would have earned an hourly rate, and she could also be an independent contractor who could charge any price she wanted.

"Private arrangements may be initiated at the first point of contact, but who can say it was just contained at the Pelican Club?

"All sorts of the most remarkable arrangements come from private client relationships and this [Versalko case] is one of those," said Ms Healy.

"It's rare, but not uncommon, to hear of clients paying huge sums of money or buying houses for them."

The Weekend Herald has received a number of emails from readers stating that prostitution is a legal profession.

One pointed out that Versalko spent a "fortune" on wine but doubted that the ASB was trying to sue the wine retailer to recoup the $300,000 he spent stocking his cellar.

"Why then should the ASB feel that it can bully a single working mother to give back the money that she was paid for the service that she provided? Is it perhaps because she is the easiest target?"

While Versalko was able to defraud the ASB of $17.8 million for nine years, the scam was unravelled in just one day when a customer rang the bank with concerns.

ASB is yet to explain how Versalko escaped detection for so long but says new procedures are in place to prevent such fraud from happening again.