Australian lottery officials are searching for a mystery ticket holder who is yet to claim a life-changing $40 million Powerball jackpot after winning the entire Division One prize.

The winning ticket was purchased from a NSW Lotteries outlet in the Australian Capital Territory, but because it was not registered, officials have no way of contacting the lucky winner.

The prize is the third-largest lottery win ever recorded in the ACT, prompting authorities to urge anyone who bought a ticket for Thursday night’s draw to check their numbers immediately.

The winning numbers were 7, 29, 25, 18, 26, 23 and 17, with Powerball 16.

Lottery officials say the unknown winner could already be an overnight multi-millionaire without even realising it and are encouraging the ticket holder to come forward to begin the prize claim process.