State pensions could be put at risk if Britain voted in favour of leaving the European Union Prime Minister David Cameron has warned.
Free buss passes and TV licenses for pensioners would also be at risk from a "black hole" in the public finances, as would National Health Service and defence spending, he said.
The government's commitment to a so-called triple lock on pensions - a yearly increase by inflation, average earnings or a minimum of 2.5 per cent, whichever is highest - could no longer be guaranteed as the shortfall in finances would require more public spending “to the tune of something like £40bn”, he told the Observer.
"You would have to start cutting things that people really value, whether it is the money going to the NHS or whether it is support for our pension system, and that could mean reviewing the triple lock,” he said, citing figures from the Institute of Fiscal Studies (IFS) and National Institute for Economic and Social Research (NIESR).
The PM denied the Remain camp were "scaremongering" but raising the state pension in the debate has drawn the ire of Brexit campaigners.
The former work and pensions secretary and Leave supporter Iain Duncan Smith called the move "vindicitive" and a "desperate attempt to bully and frighten the British people".
He said: "This is a baseless threat. The truth is that these are policy choices and the Conservative manifesto said that protecting pensioners was a priority. It is now apparent that there is nothing they will not use or jettison in their efforts to keep us in the European Union."