The Economic Community of West African States, or ECOWAS, has postponed a summit that was scheduled for Nigeria next week.
The group's current chairman, Nigerian President Umaru Yar'Adua, has been hospitalized in Saudi Arabia since late November.
An ECOWAS spokesman announced Tuesday that the summit of heads of state has been moved to January 18.
The spokesman, Sunny Ugoh, did not give a reason for the postponement, though he said the Nigerian presidency was involved with the decision.
President Yar'Adua is at King Faisal Hospital in the Saudi city of Jeddah. Officials say he is being treated for acute pericariditis, an inflammation of the membrane around the heart.
Mr. Yar'Adua is also known to suffer from a chronic kidney ailment.
It is not clear when he will return to Nigeria.
President Yar'Adua has traveled abroad several times in the past three years for medical treatment. His current stay in Saudi Arabia is his third since August.
Some information for this report was provided by AFP.