According to the Mirror, the Brazilian midfielder has detailed an 'eye-watering list' of financial stipulations that have stunned Real.
Real president Florentino Perez was confident a deal had been done, worth in the region of £56 million.
However, Leite has supposedly put the move in jeopardy by requesting £10m commission for himself, a £10m signing-on fee for the player, plus a transfer and £1m signing-on fee for Kaka's brother Digao.
This latest twist in the Kaka saga has put Chelsea on alert, but reports eminating from Italy indicate a move to Real will be finalised on Monday, with Milan owner Silvio Berlusconi insisting the situation is set to be resolved after the weekend.
"I will meet Kaka on Monday and then I'll tell you," Berlusconi said. "It is always the players who decide on their future, who have to decide how to pursue their career.
"I did all I could but in the end he took his decision."
Kaka's future has been in question since January, when Manchester City launched an audacious £100m bid to sign him.
Kaka was a bit-part player in Brazil's World Cup winning squad in 2002 but has blossomed ever since. He joined Milan from Sao Paulo back in 2003 for a fee of around €8.5m and won the Serie A title in his first season at the club.
He was a member of the Milan team that beat Liverpool in the Champions League final in 2007, while also winning the Fifa World Player of the Year award and the Ballon d'Or in that year.
A devout Christian, Kaka gained Italian citizenship in 2007 and has repeatedly stated his desire to stay in Milan.
An exasperated Kaka told Gazetto dello Sport on Tuesday: "I'll say it for the last time. The last time. I don't want to leave Milan.
"To the millions of Milan supporters, I say that I have made my choice. I have said I want to stay. Leave me in peace, please."
However, the Rossoneri's willingness to sell the Brazil star to City in the winter was reported to have unsettled him and opened the door to a possible future transfer.
£69 million - transfer fee to AC Milan
£10 million - commission fee to Kaka's father, and agent, Bosco Leite
£10 million - signing on fee for Kaka
£1 million - signing on fee and transfer of Kaka's brother Digao
Total = £90 million