London mayor says new EU proposals 'not enough'
Britain reached a deal with the EU on Monday allowing nation states to block some legislation, one of the steps Prime Minister David Cameron says he needs to persuade Britons to vote to stay in the bloc in a referendum which could be held in June.
The potential legislative block has been dubbed a red card by the British press.
"I haven't yet seen the reforms but my view on the red card thing... is it's not really going to be enough, we need to have something more," Johnson, an ally of the prime minister and a possible successor to him, told Sky News.
"I do think that the prime minister has been negotiating very hard and obviously very successfully but my view would be 'not enough' and we need to go further."
Johnson also told his regular radio phone-in show that Britain needed to be prepared to walk away but that at the moment he was happy to back the prime minister's renegotiation bid.
(Reporting by Kate Holton and Michael Holden; editing by Stephen Addison)