Rich lister Eric Watson has enjoyed a lavish two-day birthday bash in Turkey - angering investors in his collapsed finance company Hanover.

Watson, who co-owns Hanover with Mark Hotchin, enjoyed a party worth an estimated 500,000 Euros ($1.16 million) in Istanbul, Turkish publication Milliyet reported.

Among his 300 guests were hotel heiress Ozlem Onal, American political royalty Kerry Kennedy and her cousin Caroline, Greek shipping empire heiress Tina Livanos and former Miss Italy Arianna Novacco.

Watson's Swedish former girlfriend Lisa Henrickson, mother of his three-year-old son Lucas and mother-to-be of his third child, also attended.

The two-day celebration started with a Friday night cocktail party at the Ciragan Palace, followed by an exorbitant 1930s-themed dinner party at the Sirkeci train station, the original home of the Orient Express, the following night. Most of the guests jetted in from London by private planes and stayed in the ultrafashionable Four Seasons hotel.

Hanover collapsed last July, leaving about 17,000 investors owed more than $527m.

Many were angry when Hotchin flew friends to his week-long 50th birthday party at exclusive Vomo Island in Fiji last November, and Watson's celebration has done little to appease them.

News of his party angered the Exposing Unacceptable Financial Activities Association, which has been fighting for investors since the property investment company revealed its financial troubles.

"It sickens me that Eric Watson is able to continue to live a lavish lifestyle when they are so many people suffering," spokeswoman Suzanne Edmonds said.

"It actually sends a filthy message to investors. It says, 'we don't have a care in the world about your suffering'."

Masterton woman Ann Paris and her husband have $100,000 tied up in the company and said she couldn't believe the owners were continuing their champagne lifestyles.

"We've lost a lot of money. It's appalling that they're being able to continue on like this. They should have had all their assets frozen."

A spokesman for Watson said: "This was a private occasion, entirely separate to Mr Watson's business interests. Guests paid their own way. Mr Watson has no further comment."

Hanover investors agreed in December to a rescue package that would see them repaid their principal, without interest, over the next five years.

Edmonds said Hanover had been true to its word and made the first repayment last month.

But she said the owners' parties raised doubts about how serious they were about ensuring investors recovered their money. "I fail to see why authorities cannot pass urgent laws or use existing laws to freeze these directors' assets. We're in a desperate recession and people are in desperate positions."

But criticism of Watson's party failed to find favour with New Zealand Shareholders Association chairman Bruce Sheppard - who last November expressed disgust at Hotchin's Fiji bash.

He said Hanover investors had essentially agreed to give the two directors a five-year interest-free loan when they agreed to the rescue package.

"Their time to be upset and pissed off was some time ago. I went to the meeting and I had a whole bunch of really useful questions and they wouldn't let me ask them, so they can go **** themselves."

Watson was 16th equal on last year's National Business Review Rich List with an estimated $415m.