( CNN ) -- Gabon 's President Omar Bongo , Africa 's longest-serving ruler , died Monday morning , the country 's prime minister said , settling conflicting reports from government and media accounts . Gabon 's President Omar Bongo , who died Monday , was Africa 's longest-serving ruler . Calm was reported after the announcement , but Gabon 's Ministry of Defense nonetheless announced it was closing all of the country 's land , air and sea ports , according to a ministry statement . The statement , which was broadcast on state television and radio , said that in `` the best interest of the nation , the Ministry of Defense calls on the population to increase their vigilance and patriotism during this difficult and painful time the country is facing . '' In a statement , Prime Minister Jean Eyeghe Ndong said Bongo suffered cardiac arrest at a hospital in Barcelona , Spain . `` He dedicated his political life to his country and the Gabonese people , always cultivating the unity and cohesion of the Gabonese toward a true peace , '' Ndong said . The government declared a 30-day national period of mourning . Bongo , 73 , had been receiving treatment for intestinal cancer at the Quiron clinic in Barcelona , Spain , according to the Gabonews agency . Earlier in the day , the prime minister strongly refuted initial French news reports of Bongo 's death . He had vowed to lodge a protest with the French authorities about `` repeated leaks in the French press . '' Shortly afterward , hospital officials reported Bongo 's passing to Gabonese officials . Bongo took power in 1967 , seven years after the West African country 's independence from France . He imposed one-party rule a year after succeeding the country 's first president , who died in office . He allowed multiparty elections after a new constitution in 1991 , but his party has retained control of the government since then . President Obama said Bongo `` played a key role in developing and shaping the strong bilateral relationship that exists between Gabon and the United States today . '' `` President Bongo consistently emphasized the importance of seeking compromise and striving for peace , and made protecting Gabon 's natural treasures a priority , '' Obama said in a statement Monday . `` His work in conservation in his country and his commitment to conflict resolution across the continent are an important part of his legacy and will be remembered with respect . '' CNN 's Per Nyberg and Al Goodman contributed to this report .
NEW : Defense Ministry closing all of the country 's ports after leader 's death . Bongo took power in 1967 , seven years after Gabon 's independence from France . Comment: Earlier Monday , there had been conflicting reports about the state of Bongo 's health .