"Some low-life ram-raided the bloody stadium and stole four of my prize jerseys," Leitch told the Herald.
"It's not just my prize, it's robbed the public of seeing them. It's gut-wrenching, I feel like s***."
"My day has just been shattered," Leitch said in a Facebook post.
"My jerseys that were on display have been stolen... if you hear of anyone trying to flog some Warriors jerseys off please contact me.
"These jerseys are irreplaceable."
Leitch said the way he felt right now, if people told him who had them he would "go round with a baseball bat and sort them out".
"That's life, [I] have to move on for it but haven't felt this sick for years to be honest," he said.
"It's the fact they've gone in there and done that, they robbed the public of enjoying them."
Leitch said he "can't say too much" on steps he might take to try and get the prized jerseys back.
"Got a few aces up my sleeve to track them down," he said.
Leitch has been a large collector of sporting and music memorabilia since his days working as a butcher.
At the height of the Mad Butcher's popularity, stores were decked out in framed and signed jerseys.
He acquired items during his time long-time role as manager of the Kiwis' rugby league team - going on successive overseas tours with the team - as well as his close association with the Warriors NRL franchise, where he is affectionately known as 'Warrior No 19'.
Leitch also has a strong connection to the code in Canterbury. In 2019, he presented the late Bill Whitehead QSM - affectionately known as ‘Rugby League Bill' - with a Sport Canterbury lifetime achievement award during a visit to Bill's Christchurch rest home.
Leitch's work in the community has also seen him being befriended by a host of sportspeople from other codes, who have gifted him many match-worn and signed items over the years.
He said he had never bought a jersey "in my life". As well as those given to him, he had also previously purchased some at auctions.
Auckland Stadiums director James Parkinson said he was "gutted" Mt Smart was targeted and hoped the people involved would be found by police.
"We are gutted that Mt Smart Stadium Stadium was targeted by opportunistic thieves last night, the latest in a string of ram raids and thefts across Tāmaki Makaurau.
"A range of items were stolen in the raid, including 14 irreplaceable jerseys that form part of Sir Peter Leitch's collection that he donated to the Stadium, electronic devices, tools, and a vehicle, which was used to ram several access gates as they left the scene.
"We are working with NZ Police and hope they will be able to apprehend the culprits and return the stolen items to Mt Smart."
A police spokesperson said shortly after 7.30am police received a report of a burglary that occurred overnight at Mt Smart Stadium on Beasley Avenue.
"Police attended shortly after the burglary was reported. It is understood that a vehicle was used to force entry to gain access through a gate.
"They appear to have taken items from within the premises, and stole a vehicle from the premises, causing further damage to two more gates when leaving."
Enquiries are continuing.
Previously, Leitch housed his huge collection of sports memorabilia in a renovated room at the Mad Butcher's old sausage-making factory.
He would run tours of the facility on weekends.
That museum was later closed down, with Leitch keeping his display at home and in storage.
The full placement of his memorabilia occurred earlier this year, with Leitch offering fans guided tours of the collection prior to the Warriors' NRL return home matches over the past few months.
