In a setback to the Centre, the Supreme Court today refused to stay the Andhra Pradesh High Court order quashing 4.5 per cent reservation for minorities within the 27 per cent OBC quota in central educational institutions like the IITs and IIMs. Upset with the union government’s claim that the high court had wrongly assumed that the sub-quota of 4.5 per cent comprised socially and educationally backward class Muslims, Christians, Sikhs, Buddhists and Zoroastrians, the bench asked Attorney General Goolam E Vahanvati on what basis the Centre had determined the figure of 4.5 per cent.