Billy Ray Cyrus has joked he is to become a grandad.

The country musician - who is the father of Miley, 22, Braison, 20, Noah, 15, and Christopher Cody, 23, as well as adopted stepchildren Brandi, 27 and Trace, 26 - has laughed off rumours 'Wrecking Ball' hitmaker Miley is pregnant by joking about a new arrival on Twitter.

Writing on the social networking site, he said: ''Oh yes. The Big News. Was waiting for you to ask. ''Can we talk ?''

''I'm going to be a grandfather. Call me Papaw ! (sic)''

However, the 53-year-old singer insisted the announcement was a joke by reposting a doctored image previously posted on his daughter's Instagram account, which show's the 'We Can't Stop' singer receiving an ultrasound, with a pizza baby visible in the sonogram.

Alongside the image, he added: ''Yep... Papaw Cyrus.''

The prank comes just weeks after Life & Style magazine ran a cover story saying Miley, who has been dating Arnold Schwarzenegger's 21-year-old son Patrick for approximately a year, was ''pregnant and dumped''.

As well as insisting the controversial hitmaker was expecting her first child, the article insinuated the hunk had broken up with her over the pregnancy, claiming she was ''notoriously lax about birth control'', although neither parties have commented on the rumours.