DAKAR, Senegal — President Umaru Yar’Adua of Nigeria, whose chronic ill health sapped initial promises of reform and led to a constitutional crisis in his country, died Wednesday night, the information minister said in a brief interview. He was 58.

“He has died,” said the minister, Dora Akunyili, adding that Mr. Yar’Adua had expired at the presidential villa in the capital, Abuja.

Mr. Yar’Adua suffered from kidney and heart ailments, and his health had been one of the country’s top concerns for weeks, ever since he departed at the end of November for emergency treatment in Saudi Arabia.

He did not transfer power when he left. In the following months, Nigeria, already racked by low-level civil wars over oil and religion, was left in limbo. There was no center of authority, and a peace plan Mr. Yar’Adua had enacted for the violence-plagued oil-producing south seemed in danger of falling apart.