An anti-terrorism court in Pakistan has ordered the arrest of two senior police officers accused of negligence in the killing of former PM Benazir Bhutto. She died in a 2007 gun and suicide attack in the city of Rawalpindi.A special prosecutor says the officers – who include Rawalpindi's ex-police chief – had failed to make proper arrangements and then ordered the crime scene to be prematurely hosed down. A UN report released in April said the killing could have been prevented.The report – the result of a United Nations commission of inquiry – accused the Pakistani authorities of severely hampering the investigation and said no credible inquiry should rule out the possibility of involvement of members of the country's military and security establishment.The UN report also criticised the Pakistani police's decision to hose down the crime scene, and said its failure to collect and preserve evidence “inflicted irreparable damage to the investigation”.An anti-terrorism court yesterday issued warrants for the arrest of two senior police officers, said special prosecutor Chaudhry Zulfikar Ali.