London: Pornography is all set to be banned from Britain's public Wi-Fi networks by the year-end, Prime Minister David Cameron's children's czar has announced.The move, according to Claire Perry, was vital to prevent children from stumbling across adult material when using wireless internet networks in places such as cafes and railway stations, or seeing others who may be downloading it.However, one of Britain's largest internet providers has warned against the ministers' plans to block porn from public Wi-Fi, stating it could go against the law.BT was accused of ‘dragging its heels' over an agreement to filter its public wi-fi services by raising its concerns that it could open itself to legal challenges.The company claims blocking adult material from stores which use BT public wi-fi could breach a legislation, banning the interception of electronic communications.Last year it was revealed that the coffee chain Starbucks, which uses BT, had failed to filter adult material from its free wi-fi, putting children of seeing obscene porn on other customers' tablets or mobile phones.Starbucks has now imposed a filter.But Perry said she was still hopeful that hardcore porn would be filtered out of all public wi-fi networks by the end of the year.