BEIJING, Dec. 25 -- Foreign couples planning to adopt Chinese children need to have stable marriages, sound physical and mental health and comfortable finances and must not be overweight.

    The new guidelines, which go into effect on May 1, give preference to more suitable applicants, a Ministry of Civil Affairs official said yesterday.

    A key criterion is that applicants should have a Body Mass Index (BMI) a measure of body fat based on height and weight that applies to both adult men and women of less than 40.

    A BMI of 40 means extreme obesity, for example, in a person who is 1.7 metres tall and weighs more than 115 kilograms.

    Xing Kaimin, director of the ministry's China Centre of Adoption Affairs, said obese people are more likely to suffer from diseases and might have a shorter life expectancy.

    The applicant couple must be married for at least two years; and those who were earlier divorced should have been currently married for at least five years.

    Xing said a complete family is essential for adopted children.

    The current law allows single foreigners to adopt Chinese children, but requires the father to be at least 40 years older than the adopted girl.

    Another change is that couples must also have less than four children and be in the 30-50 age group, according to Xing. The current law does not specify the number of children of adopting parents, but they should be at least 30 years old.

    He stressed the guidelines are temporary and might be revised.

    "We will continue to deal with foreign adoption according to law," he told China Daily, referring to the Law of Adoption and a Registration Regulation on Foreign Adoption.

    "The priority criteria are meant to protect children's interests and shorten the waiting time for more qualified applicants," Xing said. "It does not mean we are prejudiced against less qualified applicants, who can still apply."

    Xing said the centre, the only institution authorized to deal with foreign adoptions, has received a soaring number of applications to adopt Chinese children in recent years.

    Prospective adopters now have to wait for 14 to 15 months on average from the time of their applications till they receive an initial match, Xing said.

    "We want to pick the most qualified so that our children can grow up in even better conditions," Xing said, noting there are fewer abandoned or orphaned children because of social progress.

    Xing said more than 100 licensed adoption agencies in 16 countries have been informed of the revisions.

    More than 50,000 Chinese children are reported to have been adopted by foreigners in the past 10 years, of which US families make up four in five.

    About 8,000 Chinese children were adopted by US families last year. The figure was 5,000 in 2001.