Unconfirmed reports have circulated Omar Bongo is suffering from cancer
Africa's longest-serving leader, Gabon President Omar Bongo, is said to be seriously ill in hospital in Spain.
Spanish Foreign Minister Miguel Angel Moratinos confirmed that 73-year-old Mr Bongo was receiving medical treatment in the city of Barcelona.
Unconfirmed reports have circulated that he is suffering from cancer. Mr Bongo has led his oil-producing West African state since 1967.
Mr Bongo is facing corruption investigations by French courts.
A Paris magistrate announced a landmark investigation two weeks ago into whether Mr Bongo and two other African presidents had plundered state coffers to buy luxury homes and cars in France.
Shortly afterwards, Mr Bongo announced he was suspending official duties to mourn his wife, Edith Lucie Bongo Odimba - daughter of Congo President Denis Sassou Nguesso - who died last month after a long illness.
"I can only tell you that Mr Bongo is in Spain, where he is receiving treatment in a clinic in Barcelona," said the Spanish foreign minister during a visit to the Bosnian capital Sarajevo.
An unnamed Spanish foreign ministry source told Reuters news agency Mr Bongo's condition was "stable but serious".
Barcelona's Quiron Clinic confirmed Mr Bongo was being treated there.
The Barcelona-based daily La Vanguardia said in its online edition that Mr Bongo has a "serious tumour".
He is being accompanied by his entourage, including his daughter Pascaline Bongo, according to AFP news agency.
Opposition leaders in Gabon have claimed the president's son, Ali Ben Bongo, currently defence minister, is being manoeuvred to take over one day from his father.