David Cameron declared he was "battling for Britain" as he arrived for crunch talks on his European Union reforms.
The Prime Minister arrived at the Brussels summit, billed as a "make-or-break" moment for the UK's renegotiation agenda, insisting he would not accept a deal that did not meet his demands.
If a deal is agreed at the meeting of EU leaders, it could pave the way for a referendum on the UK's membership of the EU as early as June, but Mr Cameron insisted he was not in a rush to secure an agreement at any cost.
He said: "We have got some important work to do today and tomorrow and it's going to be hard. I will be battling for Britain; if we can get a good deal I will take that deal but I will not take a deal that does not meet what we need.
"I think it is much more important to get this right than to do anything in a rush.
"But with goodwill, with hard work, we can get a better deal for Britain."