The United Arab Emirates' President Sheikh Khalifa bin Zayed al-Nahayan received medical treatment in Switzerland for undisclosed reasons after undergoing checks, the UAE state news agency said on Wednesday. Sheikh Khalifa, who is in his early 60s, is the ruler of the wealthy oil-exporting Gulf Arab emirate of Abu Dhabi and the president of the US-allied United Arab Emirates. “President HH Sheikh Khalifa Bin Zayed al-Nahayan has undergone comprehensive medical check-ups in Switzerland,” state news agency WAM said. “President HH Sheikh Khalifa then received the necessary medical treatment, which culminated in a complete success,” it added, without saying what he was treated for. It said Sheikh Khalifa was to return to the UAE after a “period of convalescence”. The UAE is a federation that unites Abu Dhabi and six other emirates including regional business hub and tourism magnet Dubai. Abu Dhabi is the seat of the federal union.