Sirius XM Radio has said it could file for bankruptcy as early as Tuesday if it fails to refinance its debt, heating up discussions with its potential saviours: Liberty Media’s John Malone and EchoStar’s Charlie Ergen.

The US satellite radio service, which broadcasts programmes from Howard Stern and Martha Stewart, said it had exchanged $172.5m of its 10 per cent convertible notes due in December for newly issued senior secured notes due in 2011.