President John Evans Atta Mills has left Accra Saturday evening for a routine medical check-up in the United States.This follows rumours about his ill health in recent times.He told reporters at the Kotoka International Airport before his departure that there was no cause for alarm and that the check-up is a normal one.The president did not indicate how long he'll be staying out but stressed he'll be away for a "few days".Vice President John Dramani Mahama will act as President in his absence.The president has been heavily criticised in the last few days for failing to speak out against the pockets of violence across the country.The calls for his comments became more prominent following the clashes which claimed three lives at Hohoe in the Volta Region.Mr Mahama was perhaps the most active in the days following the violent clashes.Sources at the Castle earlier told Joy News the president had been taking some days off to rest.Death rumourPresident Mills also condemned rumours that he has passed on."Indeed this is not the first time I've heard people say this about me...Let me just say that I'm very, very, very strong. And I don't know the basis for saying that I'm dead," he told the press at the airport."Well, let me just say that under our constitution the president has a duty to inform Parliament, to inform them whenever he's going outside the country. What I have decided to do is to go for a medical check-up. And this will not be the first time. I go there and they make sure everything is okay.""So I'm going for a few days and then come back."The ill health of the president has been played up by some members of the opposition New Patriotic Party (NPP).His critics have demanded he makes his medical records public, a challenge his aides have described as unnecessary.