David Cameron Davos Image: Valeriano Di Domenico/World Economic Forum

Prime Minister David Cameron used his speech at the World Economic Forum to urge businesses to support his case for the UK remaining in a reformed European Union

Mr Cameron has previously called on businesses to keep quiet about their preferences until the outcome of negotiations is clear, but his aim is now to canvas support from political and business leaders at the Forum in Switzerland.

At an EU summit next month, the Prime Minister then hopes to agree on the reforms. He will then likely call a cabinet meeting "soon after" any deal is struck after some members of his cabinet raised concerns that a delay to the meeting could give an unfair advantage to those in favour of remaining part of the EU.

Netherlands Prime Minister Mark Rutte was one of those in the room when Mr Cameron delivered his speech. He is considered one of the key politicians the Prime Minister needs to convince given his role as President of the European Union.

Despite starting his speech to a half-empty hall, David Cameron told businesses "don't hold back" in the campaign to keep the UK in the EU, and said they need to be "out there" giving the public context to the referendum.

And Mr Rutte handed David Cameron a huge boost in that quest. Prior to the Prime Minister's speech, his Dutch counterpart said Europe "needs" the UK to remain within the Union.

Mr Rutte said: "The UK is outward looking, trade oriented, growth oriented, and we do not have enough of that storyline, that tradition, that culture with the European Union."

In an interview with the BBC, BP chief executive Bob Dudley said the UK would be worse off if it left the EU, and suggested that the oil giant could even re-evaluate its investment in the UK.