Detectives and colleagues of a senior Pakistani opposition politician stabbed and beaten to death in a residential street in north London said tonight they were working on the assumption it was a political assassination. Imran Farooq, one of the co-founders of the Muttahida Qaumi Movement (MQM), a powerful, Karachi-based party run for almost two decades by a leadership exiled to the London suburb of Edgware, was found near his home after neighbours witnessed what they initially believed was a fight. Paramedics were called but he was pronounced dead at the scene. The 50-year-old, who was married with two young sons, claimed UK asylum in 1999 alongside Altaf Hussain, who remains the MQM's leader and has been outspoken in condemning Islamist militancy in Pakistan and the Islamabad government's response to devastating floods. News of the killing sent Karachi into mourning, with streets deserted, schools and businesses shuttered and buses taken off the roads. Several vehicles were set alight and the city, Pakistan's biggest, remained tense.