Algeria’s 81-year-old President Abdelaziz Bouteflika will seek a fifth term in April’s elections, he announced in a message published by state media.
Mr Bouteflika has been in office for 20 years but has rarely been seen in public since he had a stroke in 2013.
He insisted his “unwavering desire” to serve Algeria allowed him to “transcend the constraints of health concerns”.
Critics say this makes it difficult for him to carry out his duties.
He is confined to a wheelchair and has cancelled recent official meetings.
Mr Bouteflika’s last meeting with a senior foreign official was during a visit by German Chancellor Angela Merkel in September. An earlier meeting with her had been cancelled.
However, Mr Bouteflika is widely expected to win the April election, says BBC Arabic’s Ahmed Rouaba.
Is he the oldest world leader?
No, by quite a stretch.
The world’s oldest elected leader is 93-year-old Malaysian Prime Minister Mahathir Mohamad.
Mr Mahathir joked about his own age when he was voted in as prime minister in May.
“Yes, yes, I am still alive,” he quipped to the crowd at a news conference.
Mr Bouteflika can look closer to home to find another elected president who is quite a few years older than himself.
Algeria’s neighbour, Tunisia, is led by 92-year-old President Beji Caid Essebsi.