New York, April 18 (Inditop.com) Actor Mel Gibson may have to pay a substantial amount of child support to ex-girlfriend Oksana Grigorieva for their five-month-old daughter, Lucia following their break up.

According to attorney Steven Knowles, Gibson may have to shell out $12,000 to $15,000 a month as child support to Russian singer Grigorieva for their daughter, but probably has no legal responsibility to make alimony payments as they were not married.

“This is not dissolution of marriage action. The mother would have rights to child support, which in the case of Mr. Gibson, will be very substantial,” people.com quoted Knowles as saying.

“He is what we call a high-income earner, and there is a high-income earner stipulation that says they must pay any amount reasonably necessary for the support of the child.

“Merely living together and having a child does not give the mother any rights to property and certainly no spousal support,” said Knowles, who’s not involved in the Gibson action.

A close friend of the couple calls the split “amicable,” adding: “They’re still friends and they’ll both raise Lucia together.”

Meanwhile, Gibson is in the midst of a divorce from his wife of three decades, Robyn.