NEW DELHI: The opposition sought to corner the government in Rajya Sabha on Thursday over the Delhi riots as it accused the Delhi Police of inadequate response and alleged that the Centre had injected "communal virus'' in the city as inaction on hate speeches amounted to a licence to kill.Many MPs also raised concerns over the Citizenship (Amendment) Act (CAA) with Akali Dal MP Naresh Gujral urging the government to address fears of Muslims over the law. Initiating a short-duration debate, Congress's Kapil Sibal sought to know from home minister Amit Shah why registration of FIRs was delayed against perpetrators of hate speeches.Sibal said this had provided the perpetrators a "licence to kill" and added that "you can do anything to protect cows, but not human beings? Do we need to bring another Article to ensure protection of human beings?" He said while the government had earlier called the violence spontaneous, Shah was now saying it was a conspiracy.Trinamool Congress MP Derek O'Brien said children were the worst sufferers in the riots. Referring to National Security Advisor Ajit Doval's visit to riots-hit areas, the TMC MP asked, "If Delhi Police was doing a good job, why was the chain of command superseded and the NSA given command?"He said the CAA, along with NRC and NPR, is a "toxic combination".BJP's Sudhanshu Trivedi said it was wrong to blame Delhi Police for all that had happened and said, "The situation of the Delhi Police has become like Iraq. They are being attacked for every wrong that is happening."Trivedi claimed violence in Delhi was choreographed as it was timed with President Donald Trump's visit. He accused Congress of encouraging chants of 'azaadi' by students.AIADMK member S R Balasubramoniyan said, "The entire responsibility of the violence is on the home minister...it was called a conspiracy as US President was here."Javed Ali Khan of Samajwadi Party asked the government to give heed to SAD leader and former Punjab chief minister Parkash Singh Badal who commented that there is no democracy in the country except in Parliament and state assemblies. SAD member Naresh Gujral demanded that action be taken so that no such incident happens again.