As Brexit debates deepen in the United Kingdom, British Prime Minister David Cameron dismissed the idea that Turkey would join the bloc any time soon, joking that its current progress toward accession meant it would not become a member until the year 3000.

When British Ambassador to Turkey Richard Moore was reminded that the U.K.'s long-standing position was to support Turkish governments in their efforts to join the EU and whether he thought that the U.K.'s position regarding Turkey had changed, he said that "Cameron's comments should be understood in the light of the established U.K. policy to support Turkey's EU accession process."

A dossier produced by the Vote Leave campaign, which supports a British exit from the EU, has argued that Britain would be exposed to increased immigration and security risks from Turkey if it ever joined the EU, saying that Cameron could not stop it from becoming a member of the 28-country bloc. Penny Mordaunt, the armed forces minister in Cameron's government, told the BBC, "We are not going to be able to have a say. I do not think that the EU is going to keep Turkey out."

That prompted Cameron, who has tried to avoid clashing directly with members of his own party in the debate, to abruptly criticize Mordaunt as "absolutely wrong" in an interview on ITV's Peston on Sunday show: "Britain and every other country in the European Union has a veto on another country joining. That is a fact," dismissing the idea that Turkey would join the bloc any time soon and joking that its current progress toward accession meant it would not become a member until the year 3000.

Turkey began EU accession talks in 2005, after decades of knocking on the door of the bloc and the U.K. had been one of the firm supporters for Turkey's bid to join the union.

When asked to comment on Cameron's words, Ambassador Moore said the strict conditions for the enlargement process means that it takes many years for a country to complete accession negotiations, undertake reforms and achieve the progress needed to meet EU membership criteria.

The newly-formed Turkish government is expected to comment on Cameron's statement, which will be seen as a surprisingly negative move from a strong ally.

During a speech in the Turkish Parliament in Ankara in July 2010, Cameron said: "In terms of Turkish membership of the EU, I very much support that. I'm here to make the case for Turkey's membership of the EU. And to fight for it." He added that he wanted to "pave the road" for Turkey to join the EU, saying the country was "vital for our economy, vital for our security and vital for our diplomacy." A European Union without Turkey at its heart was "not stronger but weaker... not more secure but less... not richer but poorer."

On his first day as the new chairman of the ruling Justice and Development Party (AK Party), Binali Yıldırım said it is time for the EU to end the "confusion" over Ankara's long-standing membership bid, as well as the landmark deal on migrants. "There is one thing that needs to be done by the European Union. This confusion over Turkey's full membership and the migrant issue has to be brought to an end. It is time for us to know what the EU thinks about Turkey. We have thus far carried out all necessary reforms with determination, and will continue to improve democracy and make strides on human rights ... with or without the European Union."