"We are open for anyone to inspect the office's random procedures," said Pol Maj Gen Attagrit Tharechat, chief of the Government Lottery Office (GLO).
He said the results were based purely on chance and the lottery machines were selected to meet world standards.
The machine for the first prize was designed by King Mongkut's Institute of Technology Ladkrabang and has a plastic tank so that the draw can be seen clearly by witnesses, said Pol Maj Gen Attagrit.
In Sunday's lottery, the last three digits of the main winning number, 531404, matched Ms Yingluck’s licence plate 5404 for the minivan she used in Chiang Mai last weekend.
Moreover, the two-digit winning numbers, 79, matched her Totoya Alphard’s licence plate 7879. The car was used on her trip to the Northeast last week.
Pol Maj Gen Attagrit said the criticism is a plan to attack the GLO by a group of underground lottery bookies who lost a lot of bets due to the fact that a huge number of punters won bets on the PM's licence plate numbers.
The cash flow of the underground lottery is at least 100 billion baht per year.
Pol Maj Gen Attagrit said people like to bet on lucky numbers from obscure sources.
He said the lottery machines were all replaced by new technology after Klom Bang Kruai or Narong Ounphaet, a Nonthaburi mafia figure, fixed a June 2001 draw by marking lottery balls with a luminous chemical liquid and coaching people to select the marked balls. He was jailed for the scam.
Regarding anti-government protest leader Suthep Thaugsuban's accusation of bribery related to contract renewal for two charity lottery ticket distributors, Pol Maj Gen Attagrit said the office does not have any reason to deny the renewals if the distributors have never breached any conditions.
"If he has evidence, tell us who paid what to whom. We want transparency and straightforwardness," he said.
The GLO prints 72 million lottery tickets for each draw.