Andrew Little has lashed out at TV3 Political Editor Patrick Gower, calling him a "desperate journalist", as he got angry over questions on Labour's foreign buyer campaign.
Earlier this month Labour used leaked data based on Chinese-sounding names as proof of a foreign buyer problem in Auckland.
It said 39 percent of the names where of Chinese origin, while only 9 percent of Auckland's population was Chinese.
Mr Little was asked this morning about a TV3 story last week, in which 3 News visited some of the people on Labour's list, only to find they were actually New Zealand residents.
The Labour leader took exception to a question that included the phrase "cooked-up data", telling Mr Gower: "I'm not going to stand here and have a desperate TV3 reporter use inflammatory language on this. Cooked-up, what was cooked-up?!"
Mr Little added: "You don't understand. You're making stuff up."
In the House this afternoon, Prime Minister John Key had a crack at Mr Little after being asked questions about IRD data to be collected about non-resident taxpayers who buy houses.
"As the member knows, there's a process we're going through at the moment and we'll be looking at that data. But what I do know is that our information won't be cooked-up, and when someone asks me a question about it I won't lose my rag at TV3 like that member did before."