Kazakhstan’s President Nursultan Nazarbayev, who has led the country since independence from the Soviet Union, has announced his resignation.
In a pre-recorded television address, he said the decision had “not been simple”.
Mr Nazarbayev, 78, has been largely unchallenged since he became president of the oil-rich nation in 1990.
He has focused on economic reform while resisting moves to democratise the political system.
“I have decided to give up my powers as president,” he said during a surprise television address.
Mr Nazarbayev said the speaker of the upper house of parliament, Kassym-Jomart Tokayev, would take over as acting president for the remainder of his term.
The announcement comes just weeks after the leader sacked the country’s government, citing failures to improve the economy.
“In many areas of the economy, despite the adoption of many laws and government decisions, positive changes have not been achieved,” he said in a statement at the time.
A surprise announcement
Analysis by Abdujalil Abdurasulov, BBC News
In the past few months and even years, there has been speculation about Mr Nazarbayev’s imminent resignation.
These rumours reached a new level recently when he formally requested the Constitutional Court to clarify the process of a presidential resignation. The court confirmed that the president had a right to resign.
For many, it was clear that he would leave soon. However, his announcement today still caught many by surprise.
Mr Nazarbayev is the only president independent Kazakhstan has known. Many regarded him as a president for life, a common practice for authoritarian states in Central Asia.
He enjoyed great popularity, although it was never possible to independently measure it due to the lack of free and fair elections. Yet, because of the economic crisis, he has faced growing discontent from some of the population.
Born in 1940, Mr Nazarbayev came to power as first secretary of the Communist Party of Kazakhstan when it was a Soviet republic.
After independence, he was re-elected against largely token opponents in 1999, 2005, 2011 and – most recently – in 2015.
But the conduct of every election was criticised by foreign observers.
A huge country the size of Western Europe, Kazakhstan has vast mineral resources and enormous economic potential.
Since independence following the collapse of the Soviet Union in 1991, major investment in the oil sector has brought rapid economic growth, and eased some of the stark disparities in wealth of the 1990s.