Adds BT comment, detail, updates prices Dec 12 (Reuters) - BT Group BT.L shares fell more than 4% on Tuesday after Britain's telecom regulator proposed a ban on inflation-linked price rises in the middle of customers’ mobile and broadband contracts. BT noted Ofcom's consultation into inflation-linked pricing mechanisms and said it had always followed their guidance. "Currently, we are in the process of reviewing this consultation, and assessing our options which we will submit as part of our response," a BT Group spokesperson said.