Lagos , Nigeria ( CNN ) -- Ailing President Umaru Musa Yar'Adua has returned home to Nigeria , though it was not immediately clear whether he was well enough to resume duties . Abdullah Aminchi , Nigeria 's ambassador to Saudi Arabia -- where Yar'Adua has been receiving medical treatment since November -- said the president 's health had improved considerably and that he went back to Nigeria on Tuesday . He was treated for inflammation of tissue around the heart , a condition that was diagnosed last fall after he complained of chest pain . He was taken to King Faisal Specialist Hospital and Research Centre in Jeddah , Saudi Arabia , where he had undergone his last checkup in August , his doctor said . His absence had created a power vacuum in Africa 's most populous nation , observers said . It also sparked demonstrations in the nation 's capital , Abuja , where protesters demanded a constitutional order on his absence and evidence about his true state of health . Explainer : Will Nigeria 's leader return to power ? As a fix , Nigerian lawmakers voted earlier this month to install the country 's Vice President Goodluck Jonathan as head of state . A statement from the U.S. assistant secretary of state for the Bureau of African Affairs Wednesday welcomed the news of Yar'Adua 's return , but said he hoped that it was not `` an effort by his senior advisors to upset Nigeria 's stability and create renewed uncertainty in the democratic process . '' `` Nigeria is an extraordinarily important country to its friends and partners , and all those in positions of responsibility should put the health of the president and the best interests of the country and people of Nigeria above personal ambition or gain , '' said the statement from Assistant Secretary of State Johnnie Carson . `` As a nation of 150 million people , Nigeria 's democracy and its continued adherence to constitutional rule should be the highest priority , '' the statement added .
Unclear whether Umaru Musa Yar'Adua will resume duties . He has been treated for loss of tissue around the eye . His three months absence left a power vacuum in Nigeria .