LONDON (Reuters) - Cryptocurrency exchange Coinbase said on Thursday its retail and professional-focused platforms were hit by tech problems, with users reporting difficulty trading as bitcoin plunged towards its biggest one-day drop since September. California-based Coinbase said on its website at 14:14 GMT it was investigating connectivity problems, adding at 14:42 GMT that it had identified the problem and implemented a solution. In a separate post at 15:21 GMT on its Coinbase Pro site it said “increased latencies impacting order entry and settlement” for its Coinbase Pro service, adding it was investigating the problem. A spokesman for Coinbase, one of the biggest cryptocurrency exchanges, declined to comment. Coinbase users on Twitter reported problems trading. One Coinbase Pro user told Reuters by message: “The outage prevented me from submitting a buy limit order which would’ve been executed as the limit price was met. At this time the order finally went through but I missed the price for now.” Bitcoin, the world’s biggest cryptocurrency, slumped as much as 13% on Thursday to its lowest since Nov. 16., slamming the brakes on its red-hot rally and sparking a sell-off of smaller coins. It was last down 9% at $16,904 and on course for its biggest one-day drop since Sept 3. The move represents a sharp correction from its three-year high of its near-record $19,521 hit on Wednesday.