Bush senior, 89, joins Twitter

Former United States president George H.W. Bush has joined Twitter at the ripe old age of 89, quickly racking up 50,000 followers by Wednesday after just a single tweet.

"Barbara and I wish we could have joined the U.S. delegation honoring President Mandela today. He, and his countrymen, are in our prayers," @GeorgeHWBush wrote on Tuesday.

The senior Bush's account profile describes him simply as "41st President of the United States of America" and shows a black-and-white photo of him smiling broadly.

Bush and his wife Barbara were invited by US President Barack Obama to visit South Africa on Tuesday to pay tribute to Nelson Mandela, who died last week at the age of 95.

But the former president, who served between 1989 and 1993, declined because he can no longer travel long distances, said his spokesman Jim McGrath. (AFP)