Kazakhstan's presidential office says President Nursultan Nazarbaev is being treated for a cold and will be unable to make some planned trips abroad.
The office's October 11 announcement was unusual as Nazarbaev's state of health is rarely made public in Central Asia's largest country.
No further details on his health were provided.
The Interfax news agency quoted an unnamed diplomatic source in Azerbaijan on October 11 as saying that Nazarbaev's visit to Baku was cancelled due to the Kazakh leader's treatment for his cold.
Nazarbaev's visit to the western Kazakh region of Manghystau, which was scheduled for October 11, has also been cancelled.
Meanwhile, Armenia's presidential office announced on October 11 that Nazarbaev is still expected to travel to Yerevan on October 13 where a top-level Collective Security Treaty Organization (CSTO) summit will be held on October 14.
Nazarbaev, 76, has led oil-rich Kazakhstan with an iron fist since 1989.
In the past, he has been treated in China for undisclosed health reasons.
Also on October 11, Nazarbaev's office said the president held phone talks with acting Uzbek President Shavkat Mirziyaev, reportedly focused on bilateral ties.
Mirziyaev became acting president last month after the death of longtime Uzbek leader Islam Karimov.
With reporting by Informburo.kz