A Ministry of Health spokesperson confirmed the matter was being taken seriously.
"The ministry is aware of the allegations and understands enquiries are being made by the DHB. We are confident the appropriate steps are being taken by the DHB to establish what happened.
"We will now await the outcome," they said.
Wairarapa DHB chief executive Dale Oliff said while she was aware DHB staff had eaten at the restaurant, she did not have details, including how payment was made.
"As chief executive, I was not previously aware of a function at Wingate Lane over the weekend. I have subsequently been advised that a party comprising staff from a DHB team did meet for dinner at Wingate Lane in Masterton on Saturday evening.
"I am not aware of how the food and beverages were paid for, or who the participants were. To my knowledge the DHB did not fund the event," she said.
The tipster said a large amount of food and alcohol was bought by the revellers, using Prezzy cards.
"If Prezzy cards were used for entertainment purposes, our inquiry will determine where they were sourced," the DHB said.
"DHB policy prohibits the use of public funds for purchasing alcohol."
The tipster, who wanted to remain anonymous, had been given information about the get-together by hospital and other insiders.
"It stinks of something going on," they said.
The allegation comes soon after the DHB came under fire on social media for using Prezzy cards to encourage latecomers to get the Covid vaccine.
From November 6, people getting vaccinated were each entitled to $100 Prezzy cards, issued at vaccination centres.
At a DHB board meeting on Monday Oliff defended the use of the cards, saying the incentive had boosted vaccine numbers.
It had also encouraged vaccination among those in the 18- to 30-year-old group previously slow to come forward.
An evening out at Wingate Lane doesn't come cheap. Most starters are around $16, while mains could set you back as much as $38. Most bottles of wine are from $40 to $55.
The Wairarapa DHB spokesperson said financial controls were in place to manage financial incentives, including Prezzy cards.
"A process has been developed to manage and monitor the use of incentives, which requires Wairarapa DHB vaccination team staff to reconcile the gift cards against the Covid immunisation register daily.
"As the incentive scheme was only launched four weeks ago, no audit of the gift card system has yet been carried out. All financial aspects of DHB business are subject to financial control and audit.
"The process for managing cards is expected to be followed by all staff involved in the ordering and distribution of cards. The gift cards are stored in a safe until they are provided to people having received their first dose. They should not be used for any other purpose."
The owners of Wingate Lane have been approached for comment.
