Chief 'In' campaigner Prime Minister David Cameron clashed with members of his own party on Sunday over the impending referendum on Britain's European Union membership, dismissing claims that he would be powerless to stop Turkey joining the EU.
Cameron is leading the campaign to keep Britain inside the EU ahead of the June 23 referendum, the outcome of which will have far-reaching consequences for the country's economy, its role in world trade and its global diplomatic status.
But many in his Conservative Party, including several cabinet ministers, are campaigning to leave the bloc, raising the prospect that a long-standing rift over Europe could become a permanent split and threaten Cameron's ability to govern after the vote.
'Out' campaigners sought to seize the initiative on Sunday by focusing on immigration, one of the most emotive issues in the Brexit debate, after six out of the last seven polls in the last week showed the Remain campaign in the lead.
A 'Vote Leave' dossier said 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 becoming a member of the 28-country bloc.
"We are not going to be able to have a say. I do not think that the EU is going to keep Turkey out," Penny Mordaunt, a junior defence minister in Cameron's government, told the BBC.
That prompted Cameron, who has tried to avoid clashing directly with members of his own party in the debate, to abruptly criticise 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," he said.
"And the fact that the 'Leave' campaign are getting things as straightforward as this wrong I think should call into question the whole judgement in making the bigger argument about leaving the EU."
He also dismissed the idea that Turkey would join the bloc any time soon, joking that its current progress towards accession meant it would not become a member until the year 3000.
Highlighting a schism that extends far into the upper echelons of the party, both campaigns later issued briefing notes criticising senior Conservatives in the rival campaign, including pro-EU finance minister George Osborne and the figurehead of the Brexit campaign, Boris Johnson.
Turkey began its EU accession talks in 2005 after decades of knocking on the door but progress has been very slow due to a range of issues, including its human rights record.
Cameron also warned voters that they would face higher grocery bills if the country decides to leave the EU, citing a potential drop in the value of sterling.
"Independent studies show that a vote to leave would hit the value of the pound, making imports more expensive and raising prices in the shops," he said in a statement.
His comments mark a shift in campaign tactics by the 'In' side: a push to make explicit the link between the macroeconomic risks that have dominated the Brexit debate so far, and their potential impact on Britons' daily lives.
The warning comes from a government analysis of the short-term impact that a British exit would have on voters. It modelled a 12 percent fall in the value of sterling, a figure it said was based on external impact assessments, and predicted the effect on prices after two years.
The analysis said the average family's weekly food and drink bill would rise by almost 3 percent, or 120 pounds ($175) per year, and that clothing and footwear costs would rise by 5 percent, or 100 pounds per year.
However, the rival 'Out' campaign disputed the analysis, saying that "protectionist" EU policies pushed up prices.