Former President George H.W. Bush joins Twitter

(Reuters) - George H.W. Bush has joined Twitter and in his first tweet the former U.S. president said he wished he could have attended the memorial service for Nelson Mandela in South Africa. Bush, 89, who had a health scare a year ago, was the only one of the four former American presidents still living who did not attend Tuesday's memorial service in Johannesburg. "Barbara and I wish we could have joined the U.S. delegation honoring President Mandela today. He, and his countrymen, are in our prayers," Bush tweeted. President Barack Obama led a delegation that included former presidents Bill Clinton, Jimmy Carter and George W. Bush, Bush's son. Clinton, who has grown close to the elder Bush while working together on relief for the Asian tsunami and other projects, welcomed to Twitter the man he beat in the 1992 election. "Congratulations on joining Twitter, Mr. President! Easier than skydiving!" Clinton wrote, referring to Bush's past habit of celebrating milestone birthdays by parachuting. Bush is the third current or former president to join Twitter, after Obama and Clinton. Carter and George W. Bush have yet to join the popular social media service. (This story has been corrected to make clear that elder Bush worked with Clinton on tsunami relief.) (Reporting by Eric Beech in Washington; Editing by David Brunnstrom)