Supreme Court today said the validity of the Centre''s ordinance allowing states to conduct separate entrance tests for admission to MBBS and BDS courses for the 2016-17 academic year was "in doubt", but rejected a plea seeking a stay on it saying half the states have already conducted their tests.

"It is disturbing and not proper for the government to bring an ordinance allowing states to hold their own tests despite our orders..Prima facie, we find that the validity of the ordinance is in doubt," a bench comprising Justices A R Dave, A K Goel and Shiv Kirti Singh said.

It also dismissed the plea for centralised counselling of successful candidates of various entrance tests, saying "50 per cent states have conducted their tests."

The apex court was hearing pleas filed by Anand Rai, who claims to be a whistle blower in the Vyapam scam, and others challenging the ordinance saying the Centre was not competent to nullify the judicial order by promulgating the ordinance, reported PTI.

Attorney General Mukul Rohatgi had earlier told the court that the ordinance, which keeps state boards outside the purview of single medical entrance test NEET, is only for this academic year and the government was well within its right to come up with it.

Rai in his plea had sought quashing of the ordinance, which got Presidential assent on May 24, and sought a stay on its operation as an interim relief.

The apex court had on May 9 rejected the pleas of state governments and minority institutions to allow them to hold separate entrance exams for MBBS and BDS courses for 2016-17, saying only National Eligibility cum Entrance Test (NEET) provides for conducting test for admission to these courses.

The top court had approved the schedule put before it by the Centre, CBSE and Medical Medical Council of India (MCI) for treating All India Pre-Medical Test (AIPMT) fixed for May one as NEET-1.

It had said that those who have not applied for AIPMT will be given opportunity to appear in NEET-II on July 24 and the combined result would be declared on August 17, so that the admission process is completed by September 30.