David Cameron has made his first public pitch to the British electorate since securing his EU renegotiation deal by urging undecided voters to consider the uncertainties of a breakaway from Brussels before casting their vote in the 23 June referendum.

"In the end it will be your choice, the British people's choice. If you choose to stay in, we know what we get. If you choose to leave, I will put in place the arrangements as your prime minister that you asked me to do," the prime minister argued in a speech on 23 February.

"But my strong advice, with all that I have seen and all that I know, is the right thing for Britain is to stay in a reformed Europe."

Cameron, speaking at O2's UK headquarters in Slough, also repeated the claim that he had no political agenda in backing a "remain" vote at the referendum because he would not be seeking re-election at the 2020 general election.

The remark was seen as a veiled attack on Mayor of London Boris Johnson, who defied the prime minister and backed a Brexit. Some commentators have claimed Johnson made the move in order to position himself for a future Tory leadership contest.

But Cameron paid tribute to his fellow Old Etonian when he was quizzed on the matter. "He is a great friend of mine, he is a great Mayor of London," the Conservative leader stressed. "But on this issue I think he's got it wrong, and I think he's reached the wrong conclusion."

Mayor of London Boris Johnson backs a Brexit IBTimes UK

Elsewhere, Eurosceptic cabinet minister Chris Grayling warned a "remain" vote would endorse a number a number of changes made under the controversial Lisbon Treaty.

"I opposed the Lisbon Treaty because it gave too much control to EU judges over our courts and over our justice system. It centralised power further in Brussels and created a new EU president. It also increased the cost of the EU for British taxpayers," the leader of the House of Commons said.

"I opposed the EU taking more power from Britain then and I continue to oppose it now. I want the UK to take back control and for us to once more be able to vote for the people who make our laws. That's why I will Vote Leave."

The latest online opinion poll from ICM, of more than 2,000 people between 19 and 22 February, had "remain" two points ahead of "leave" (42% versus 40%), with 17% of respondents undecided.