Bollywood superstar Shah Rukh Khan is under investigation by Indian officials amid reports the father-to-be has broken the law by discovering the sex of his unborn child.

The actor and his wife, Gauri, are reportedly expecting their third child via a surrogate, and recent rumours suggested the couple was set to welcome a baby boy to the family - a brother for their 15-year-old son Aryan and 13-year-old daughter Suhana.

The Khans, who live in Mumbai, have yet to confirm claims they are to become parents again, but a formal complaint has been filed against the star and his wife by a member of the Indian Radiological and Imaging Association (Iria).

Tests to determine the sex of a child during pregnancy are banned to prevent the abortion of female fetuses in favour of male heirs.

Dr. Jignesh Thakkar tells the Afp, "We want to know the truth, and if it is true how (the gender) came out and who told it (sic). Whoever is responsible must be punished."

A representative for the state's health ministry has since ordered city officials to look into the matter, but Khan, 47, was not home on Monday (17Jun13) when authorities tried to question him about the allegations, according to the Press Trust of India.