Namibia’s President Hage Geingob, 82, is flying to the US to receive “specialised” medical treatment for cancer, his office has said.
It comes less than a week after his office said that medical tests revealed that he had “cancerous cells”.
The 82-year-old would receive “novel therapy” in the US for a week, before returning to continue with his treatment in Namibia, his office added.
Vice-President Nangolo Mumba will be acting president during his absence.
Concerns about Mr Geingob’s health have been growing, with reports saying that he admitted last year that he had become frail.
“You see how I’m standing here? It means I’m tired and I’m not feeling well,” the privately owned Namibian newspaper quoted him as telling journalists.
Mr Geingob is due to step down at the end of his two terms later this year.
In a statement on Tuesday, the vice-president of the governing Swapo party, Netumbo Nandi-Ndaitwah, said Mr Geingob was in “good spirits” and receiving “good medical attention”.
She appealed to Namibians to allow Mr Geingob and his family to focus on his recovery and healing process without speculation.
The president’s office said he would return from the US on 2 February, and 95% of the treatment for the cancerous cells would be carried out in Namibia.
Last week, it said that doctors had done a colonoscopy and a gastroscopy on the president. This was followed by a biopsy, which revealed cancerous cells.
His office did not give further details of Mr Geingob’s condition, but said at the time that he would continue with his presidential duties.
Mr Geingob underwent an aortic operation last year, while in 2014 he revealed that he had survived prostate cancer.
Namibia is due to hold presidential and parliamentary elections in November.
Swapo, which has been in power since independence in 1990, has chosen Mrs Nandi-Ndaitwah as its presidential candidate.
She is currently also Namibia’s deputy prime minister, and will become the country’s first female president if she wins.