Applications for a child's Spanish passport require both parents' permission and documents presented in person

Chilling figures revealed recently that around 2,500 children in Spain go missing every year – and most are believed, or proven, to have been kidnapped by one of their parents.

Where a couple is separated, a parent who takes the child abroad without the knowledge and permission of the other can be charged with abduction.

The government wants to prevent this as far as possible by requiring the express consent of both parents for a passport application.

This does not apply where one parent has lost custody or access rights to the child, for example through domestic violence.

But it is not clear where this leaves mothers who have no contact with the fathers of their children – where he has left her, refused to become involved when she announced her pregnancy, or does not even know, particularly where the child is a result of a one-night stand or casual relationship – likewise, in cases where the mother has left the children with their father and has no contact with them.

In these cases, it should be possible for the single parent to obtain a passport for his or her child, although some fear an administrative obstacle course might await them.

Another issue of modern society which presents a grey area that has not been publicly clarified by the government is where parent who lives with the child is homosexual and became a father through a surrogate mother, or became a mum through an arrangement with a donor not involving a sperm bank or fertility clinic.

At present, surrogacy is not legally recognised in Spain and the woman who bore the child is considered to be his or her mother, meaning her permission would be required if the adults the youngster lives with wanted to apply for a junior passport.

But although the physical presence of the adult passport applicant is now required to process the document, only one parent is required to do so, which should reduce problems in the above situations.

Now, the parent applying will have to present his or her DNI – Spanish national identity card – and that of the child, with biometric photographs, a receipt for payment of the fee and a hard copy of the application.

New passports for adults or children in Spain now require fingerprints and all will have electronic chips which can be scanned at passport control.

This move will not affect British parents, or those of any other nationality, living in Spain with their children, but will be the case if their child was born in the country and holds Spanish citizenship.

Otherwise, where underage children living in Spain retain the nationality of one or both of their parents and are not eligible for a Spanish passport, the process involved is as stated by the embassy or passport authorities of that country.

For adults and children with Spanish nationality, many countries allow the DNI national identity card to be used instead of a passport for crossing their borders.