Mr Fratutescu, who is 47 and a Romanian national, is being sought by officers in connection with the alleged offence, which is said to have occurred in May 2016.
He is described as being of slim build and around 5ft 7ins tall.
He is also known to wear glasses.
Detective Inspector Victoria Lawrance, of the Bradford District Safeguarding Unit, said:
“We have made extensive enquiries to trace Mr Fratutescu and are now appealing to the public to help us find him.
“The allegations are of a serious nature and it is important we find him, so we can speak to him about them.
“We do not believe he poses a wider risk to the public, but would ask for anyone who sees him not approach him and contact police.
“Anyone with information on his whereabouts is asked to contact the Bradford District Safeguarding Unit on 101.”