Hugh Grant announced on Saturday that he had fathered a baby boy, while pleading for privacy from media inquiries.
"In answer to some journos (journalists)," the British actor posted on the social media website Twitter, "am thrilled my daughter now has a brother. Adore them both to an uncool degree. They have a fab mum."
"And to be crystal clear. I am the Daddy," he added in a second tweet.
Grant, 52, who is best known for such films as "Notting Hill" and "About a Boy," did not reveal the child's name on Twitter.
The actor and Hong had their first child in 2011, when his spokeswoman said in a statement that the baby girl was the result of a "fleeting affair" but Grant "could not be happier or more supportive."
Days later, Hong won a court injunction in Britain "prohibiting harassment" of her and the child after she said paparazzi had made her life unbearable. Grant is a strident critic of Britain's tabloid newspaper culture.
On his Twitter message on Saturday, Grant mentioned that the press had obtained his baby boy's birth certificate and were making inquiries. "Now I've confirmed ... hoping my family will be left in peace," he wrote.
(Reporting by Alex Dobuzinskis; Editing by Dan Whitcomb and Paul Simao)