Robbers have stolen at least 3.7 million dollars from a bank in Karachi in what is being called Pakistan's biggest bank heist. The robbery took place at the main branch of Allied Bank, one of Pakistan's largest banks, less than 100 metres from city police headquarters. Police say the gang was led by one of the bank's guards. The robbers broke into the main vault and stole foreign currency worth 311 million rupees. Police have launched an investigation, but have so far made no arrests. Police will be looking for any connection between the robbers in this latest case and militants active in Pakistan and Afghanistan.<br/><br/>