07/06/2007 AT 02:30 PM EDT
A Croatian woman is suing ER
star Goran Visnjic, claiming he is the father of her 4-month-old daughter.
Mirela Rupic, 36, took legal action after Visnjic refused to recognize the child as his own, her attorney, Nenad Skare, told the Associated Press.
Skare said Rupic tried to settle the matter directly with the actor, but was not able to do so. Should Visnjic formally deny paternity, she will request a paternity test, Skare said.
Rupic told Friday's Jutarnji List
newspaper that Visnjic "knew about my pregnancy from the start." She said she'd decided to sue after the actor told her recently he would support the child financially, but would not recognize her as his daughter.
Visnjic, 34, has been married to Croatian artist Ivana Vrdoljak since 1999. In May, the Los Angeles-based couple announced they had adopted a boy
they named Tin, born at L.A.'s Cedars Sinai Medical Center on April 19.
A rep for Visnjic, who plays Dr. Luka Kovac on the long-running NBC series, could not be reached for comment.