Conservatives and Liberal Democrats are at loggerheads over proposals to tighten up the law on knife crime.
Justice Secretary Chris Grayling wants to bring in an automatic six-month jail term for anyone convicted of a second crime involving a knife.
But the chief secretary to the Treasury, Danny Alexander, is concerned that the move would be expensive and put too much pressure on prison places.
A leaked letter from Mr Alexander to Nick Clegg, published in the Daily Mail, says:
‘It is very hard to see how it could be afforded. The Treasury does not support this amendment and I am not willing to clear it."
More top news
The Republican presidential candidate's Hollywood Walk of Fame star has been vandalised again.
Ukip has "formally reprimanded" Mike Hookem over a scuffle with colleague Steven Woolfe which landed the latter in hospital.
Popular cleaning products promoted as being fine to be flushed doing the toilet are being blamed for clogging drains and causing floods.