Woody Allen has admitted Ronan Farrow ''looks a lot like'' Frank Sinatra.

The 'Blue Jasmine' director addressed his ex-partner Mia Farrow's recent claims that their only biological child's real father could be the legendary late singer in an open letter, in which he strongly denied molesting their adopted daughter Dylan Farrow when she was seven.

Responding to the speculation for the first time, the 78-year-old star wrote in the New York Times: ''Is he my son or, as Mia suggests, Frank Sinatra's? Granted, he looks a lot like Frank with the blue eyes and facial features, but if so what does this say? That all during the custody hearing Mia lied under oath and falsely represented Ronan as our son?''

He added: ''Even if he is not Frank's, the possibility she raises that he could be, indicates she was secretly intimate with him during our years. Not to mention all the money I paid for child support. Was I supporting Frank's son? Again, I want to call attention to the integrity and honesty of a person who conducts her life like that.''

The 'Rosemary's Baby' actress, who was married to the 'That's Life' hitmaker from 1966 to 1968 and continued to have an on/off romance with him following their divorce, sparked controversy when she told Vanity Fair magazine in October that Sinatra, who died in 1998, could ''possibly'' be 26-year-old Ronan's father.

Nancy Sinatra, the singer's daughter from his marriage to first wife Nancy Barbato Sinatra, also acknowledged Ronan as part of her family last year and said he ''is a big part of us, and we are blessed to have him in our lives.''