Spain's two-time Formula One world champion Fernando Alonso will sign a five-year contract with Ferrari worth 25 million euros a season, Spanish radio said on Tuesday.
The deal will be announced on Thursday, Cadena Ser radio said.
Alonso is under contract with Renault until 2010 but has the option of leaving at the end of this year.
At Ferrari, he will receive a salary of 25 million euros (36 million dollars) a season for five years, with the option of extending the contract by one more year.
If he completes six years with Ferrari, Alonso will be 34 and could then retire from the sport, Cadena Ser said.
After winning the drivers' championship with Renault in 2005 and 2006, Alonso spent an unhappy year with McLaren before returning to the French constructor last year.
Speculation has been rife in the Formula One paddock of an impending move by Alonso to Ferrari, where he would replace Finland's Kimi Raikkonen, who would then move to McLaren.
The respected autosport.com website said that once the Alonso announcement is made, Renault was expected to confirm that Polish driver Robert Kubica will lead its team in 2010.