The Duke of Cambridge has sparked speculation about his personal stance on the forthcoming EU referendum, after describing Britain as always being an "outward-looking" country. The second-in-line to the throne made the remark during a speech to the Foreign Office's Diplomatic Academy on 16 February.

"For centuries, Britain has been an outward-looking nation, hemmed in by sea we have always looked to explore what is beyond the horizon," Prince William said. "That sense of mission and curiosity is something that I know continues to drive our economy, our cultural and educational exports and our armed forces and diplomatic service."

The 33-year-old also told his audience that the UK had a "long and proud tradition of seeking out allies". The comments come at a politically sensitive time – as David Cameron is hoping to wrap up his renegotiation with the EU to make way for a reported 23 June vote.

But Clarence House has denied that William's speech had anything to do with the historic ballot. "The speech was not about Europe," a spokeswoman for the duke told IBTimes UK. However, the remarks were reminiscent to voters of the Queen's intervention in the 2014 Scottish independence referendum.

The monarch, who is constitutionally bound to be neutral on political matters, told a well-wisher that she hoped "people will think very carefully about the future" when quizzed on the referendum question near her Balmoral home in Scotland.

Liz Bilney, the chief executive of the Leave.EU campaign, said: "His Royal Highness's [words] to diplomats about maintaining partnerships as crucial to our country's interests is of course right, but it is taking a leap to suggest that this means we have to stay inside a failing institution like the European Union that does not always represent our interests or our views.

"Commentators with a keen eye might have noticed that he listed organisations he presumably felt valuable, such as Nato and the United Nations, but did not explicitly state the EU. I could just as easily claim that this commission signalled Prince William believes we should not give any importance to the EU, but I would not wish to be so presumptuous."

Elsewhere, the prime minister is meeting with EU grandees and senior MEPs in Brussels to discuss his draft settlement. A telephone poll from ComRes for ITV News, of more than 1,000 people between 11 and 14 February, put 'remain' eight points ahead of ' leave' (49% versus 41%), with 10% of respondents undecided.