Staying Power: The World's Longest-serving Leaders

Following the announcement by Cambodian Prime Minister Hun Sen that he was stepping down after nearly four decades in power, here are the world's longest-serving leaders, except for monarchs.

Equatorial Guinea: The Soviet Union was still a decade from collapse when Teodoro Obiang Nguema came to power in a coup in the west African state of Equatorial Guinea in 1979.

Under his repressive nearly-44-year rule, Equatorial Guinea has become known as the "North Korea of Africa".

Cameroon: The world's oldest elected leader is 90-year-old Cameroonian President Paul Biya, who has ruled with an iron fist since November 1982.

Nicknamed "the Sphinx" for his inscrutable nature, leader, he won a seventh consecutive term in 2018 after elections marred by allegations of fraud.

Republic of Congo (also known as Congo-Brazzaville): Denis Sassou Nguesso, 78, has spent 38 years at the helm of the country in central Africa. He was president from 1979 to 1992, then returned in 1997 after a civil war and has remained in power ever since.

Uganda: Ugandan President Yoweri Museveni, 78, has led the central African country for 37 years. He was re-elected to a contested sixth term in 2021.

Iran: Ayatollah Ali Khamenei has been supreme leader of the Islamic republic since the death of Ayatollah Ruhollah Khomeini in 1989.

Tajikistan: Emomali Rakhmon, a former collective farm boss who came to power shortly after the collapse of the Soviet Union, has had a firm grip on his poor, mountainous country for 30 years.

Eritrea: Former rebel leader Isaias Afwerki has been president of the reclusive Horn of Africa nation of Eritrea since it won independence from Ethiopia in May 1993.

Belarus: President Alexander Lukashenko, a close ally of Russian President Vladimir Putin, has used Soviet-style repression to remain in power in Ukraine's neighbour for 29 years.

Djibouti: President Ismail Omar Guelleh, who was re-elected to a fifth term in 2021, has been leader of the country that styles itself the "Dubai of Africa", for 24 years.

Russia: Putin became prime minister in August 1999, then president the following year, and served two terms before swapping jobs with prime minister Dmitry Medvedev in 2008 only to reclaim the role of Kremlin leader in 2012.

Rwanda: Paul Kagame, a former Tutsi rebel leader who put an end to the Rwandan genocide of 1994, has been president of the small mountainous nation since 2000.

Syria: President Bashar al-Assad, who has clung onto power through a 12-year civil war, has also been in power for 23 years.

The longest-serving leader in history was Cuba's revolutionary hero Fidel Castro, who spent 49 years in power. When he handed over in 2008 in his early 80s, it was to his brother Raul.