New Delhi, April 9 :    New Delhi, April 9:  The Supreme Court today called the bluff of the West Bengal government in the sex determination case, holding it was unbelievable that only about 500 ultrasound clinics are functioning in the state. 'Calcutta itself being a big city, it would have more than 500 clinics,' a three-judge bench of Justices M.B. Shah, B.P. Singh and Hotoi Khetoho Sema observed when the state health secretary submitted the report of the survey conducted by the health department. The state had earlier submitted that there are only over 200 ultrasound clinics. However, during today's proceedings it clarified that the health department survey showed that there are many more, indirectly admitting that these few hundred clinics were unregistered and illegal. The apex court had ordered a thorough survey to felicitate the closure of unregistered sex determination and pregnancy termination laboratories. The case has come before the apex court on a public interest litigation filed by social action group Centre for Health and Allied Themes (Cehat), health activist Dr Sabu George, and Masum, a women's organisation based in Pune. The petitioners contended that female foeticide has increased and, because of pre-natal sex determination, female foetuses have been aborted in the womb. The male-female ratio has decreased from 935 (females per thousand males) to 903 in the urban areas of the country. In rural sections, it has dropped from 948 to 934. In Bengal, the ratios declined from 955 to 948 in urban areas and 969 to 967 in rural regions. The petitioners contended that it was unbelievable that only 500 scan clinics have been found in a state like Bengal, especially as more than 680 clinics have been surveyed in a comparatively smaller state like Rajasthan. The apex court, which had asked health secretaries of nine states to be present at today's hearings, directed the secretaries of Bengal and Delhi to be present at the next hearing, fixed after two weeks, with more detailed survey reports. The health secretaries of Bihar, Kerala, Uttar Pradesh, Gujarat, Jharkhand, Orissa and Pondicherry were discharged as they had filed a detailed survey report and taken appropriate action. The court also withdrew its earlier summons to the Assam chief secretary, but ordered its health secretary to file a compliance affidavit giving details of the survey, including the number of illegal clinics found in the state and the action taken against them. In Tamil Nadu, the government had seized 51 sex-testing machines. One of the affected laboratories, M.V. Diabetese Clinic, sought the Supreme Court's permission for its application for registration to be accepted by the state government. The apex court directed that the clinic should be registered under Pre-Natal Diagnostic Technics Act, though the clinic claimed it was only treating diabetics.