(ECNS) -- Demand for judicial DNA identification has mushroomed in Southwest China's Sichuan Province after China decided to register all of its citizens, including the "black" population, or those born illegally under the previous one-child policy.

Sichuan Genegle Forensic Institute said it received about 300 phone enquiries regarding DNA testing during this year's Spring Festival holiday from Feb 7 to Feb 13. It also performed 40 examinations after having done none in recent years.

The institute, one of the most authoritative in Southwest China, had to continue work during the holiday. Demand for DNA identification comes from two streams: personal or judicial purposes, with the latter used to qualify for a hukou, or household registration.

Another forensic science institute in Chengdu also finished DNA tests for more than 100 people, seeing its daily business triple.

The strong demand came after the State Council said it will "remove illegal restrictions to a citizen's right to a hukou", ordering local authorities to register a child regardless of the legality of their birth.

According to 2010 national census data, China has around 13 million unregistered, or "black", citizens. Local authorities may have refused to register children born in breach of the family planning policy, or parents of such children may have not registered them out of fear of punishment.

Wu Feng, the deputy chairman of the Sichuan Association of Forensic Science, said most of the unregistered citizens in the provincial city of Chengdu are those born in violation of the now-abolished one-child policy.

Wu also said, as Sichuan has not laid out specific measures to register the citizens, that many families are seeking advice regarding DNA identification for judicial purposes and demand is expected to be stronger.