Pascal Yoadimnadji, the prime minister of Chad, has died in Paris after he was flown there for treatment following a heart attack, the government said on Friday.
Yoadimnadji, a former agriculture minister, was named prime minister in February 2005 by the president, Idriss Deby, who seized power in a military coup in 1990.
He served several times as a minister, was president of the national electoral commission in 1996 and a former president of the Chad's constitutional council.
The 56-year-old had been instrumental in implementing reforms in the country's oil sector and oversaw the daily running of government.
He was re-appointed last year after Deby won a fresh five-year term at elections boycotted by the opposition in the impoverished, landlocked central African state.
Fighting
Despite becoming one of Africa's most recent oil producers, Chad remains near the bottom of the continent's development indices.
Deby's government faces a low-intensity conflict with rebels in eastern Chad as well as ethnic conflict spilling across the border from the neighbouring Sudanese region of Darfur.
The fighting has displaced tens of thousands of Chadians.
When Yoadimnadji was admitted to hospital on Friday, government sources said the infrastructure minister, Adoum Younousmi would take over as the interim head of the cabinet.