FILE PHOTO: Kazakhstan's President Nursultan Nazarbayev attends the opening ceremony of the Astana International Financial Centre (AIFC) in Astana, Kazakhstan July 5, 2018. REUTERS/Mukhtar Kholdorbekov

ALMATY (Reuters) - Kazakh President Nursultan Nazarbayev dismissed his chief of staff Adilbek Zhaksybekov on Monday, replacing him with the mayor of the capital Astana, Aset Isekeshev.

Presidential chiefs of staff have wielded significant power under Nazarbayev as gatekeepers to the president, now 78, who has ruled Kazakhstan since 1989, the only Soviet-era leader still in power in a former Soviet republic.

Isekeshev, 47, previously served as a presidential aide and government minister. Nazarbayev has yet to name his replacement as mayor.

Nazarbayev’s office said Zhaksybekov, 64, had been dismissed because he had reached retirement age. He was two years into his second stint as chief of staff, having earlier held the post from 2004 to 2008.

Zhaksybekov’s family controls several large businesses, including Tsesnabank, Kazakhstan’s second biggest lender by assets, which said this month it had taken out a short-term central bank loan to boost liquidity.

Corporation Tsesna, a holding company for those businesses, said on Monday Zhaksybekov has become its chairman.