Labour MP Shane Jones has accused the Countdown supermarket chain of intimidating Lotto New Zealand into handing over hundreds of thousands of dollars.
The company is already under investigation by the Commerce Commission for alleged anti-competitive behaviour.
Speaking under Parliamentary privilege, Mr Jones said he had received an email claiming Countdown threatened to close its Lotto counters unless Lotto made payments worth hundreds of thousands of dollars.
He said that in exchange, Lotto can now sell its tickets at the checkouts.
Mr Jones said he would add the email to the avalanche of information being sent to the Commerce Commission.