Netizens have taken to Twitter to wish the prime minister's wife Rosmah Mansor a 'happy birthday' as she celebrates the start of her 64th year today.

'Happy birthday, mother of Malaysians Rosmah Mansor, may you become more wealthy, young, pretty and stylish,' said one user using the Twitter handle @FruttiBulat.

Twitter user @LeenIrham2 wished: 'Happy Birthday Rosmah Mansor! May you always have a long, fortunate and blessed life'.

Another user @Safiqfirdaus said: 'Happy birthday Rosmah Mansor, may you be happy with your beloved, stay gorgeous'.

Some Twitter users expressed surprise that Rosmah was now 64 years old.

'Rosmah is 64 years old? Damn, I thought she's just 20 plus,' said Twitter user @booyyaaaaa.

Another user @mdshazuwan_azmi said: 'Many do not believe that Rosmah is 64 years old. Even I don't believe it.'

Rosmah's birthday coincided with the opening of the Umno annual general assembly in Kuala Lumpur today.

Other personalities born on Dec 10, 1951 include country singer Johnny Rodriguez and Norwegian singer and actress Ellen Nikolaysen.