BEIJING, May 29 (Xinhua) -- A senior official with China's quality watchdog reiterated on Thursday that companies found to have produced substandard building materials for collapsed schools in the quake zone would receive severe punishments.

    Relief materials, both domestic and foreign, have been pouring into China following a devastating 8.0-magnitude earthquake which hit the southwestern Sichuan Province on May 12.

    Zhi Shuping, deputy director with the General Administration of Quality Supervision, Inspection and Quarantine (GAQSIQ), said companies involved in the quality scandal would face fines, factory closures and criminal liabilities according to the laws and the severity of their violation.

    He said the quality inspectors had identified the building materials as the top priority in their investigation.

    Zhi revealed the administration had seized 18 kilograms of used cotton in 300 quake-relief quilts delivered from Baoji of northwestern Shan'xi Province and immediately returned them to the producer.

    The factory was sealed off after an overnight quality inspection.

    According to a regulation issued last year, companies having severe quality problems would be imposed fines that are 10 times their profits and some would go bankrupt.

    Zhi said used blankets, which were sources of infectious diseases, were also found in the relief materials supplied by some foreign countries. They had been returned to the suppliers.

    "We will keep a close watch over any relief material from anywhere as we must be responsible for people's health."