Security in the city has been tightened today with some Muslim organisations announcing an award of Rs 1 lakh to “blacken” the face of author Salman Rushdie, who is here after a gap of 16 years.‘‘We have taken appropriate security precautions to ensure there is no law and order problem,’’ Additional Police Commissioner (Special Branch) Bipin Bihari said.The Muslim organisations have also planned to stage a dharna today at Azad Maidan. Rushdie, with girlfriend Padma Lakshmi, is at a South Mumbai hotel.