ALMATY (Reuters) - Islam Karimov, authoritarian president of ex-Soviet Uzbekistan for more than 25 years, has died, officials confirmed on Friday, and in an early sign of who might succeed him, his prime minister was designated mourner-in-chief at his funeral.

Karimov, who was 78 and served as Uzbekistan’s president from the moment it became independent from the Soviet Union, had been in hospital after suffering a stroke. He will be buried on Saturday in his home city of Samarkand.

“He has left us,” Karimov’s younger daughter Lola Karimova-Tillyaeva wrote on Instagram. “God bless him.”

He did not designate a political heir, and analysts say the transition of power is likely to be decided behind closed doors by a small group of senior officials and family members. That would preserve the system of rule Karimov established.

If they fail to agree on a compromise, however, open confrontation could destabilise the mainly Muslim state of 32 million people, which shares a border with Afghanistan and has become a target for Islamist militants. The country is a major cotton exporter and is also rich in gold and natural gas.

Unrest there would have repercussions for Russia, the regional power and home to hundreds of thousands of Uzbek migrant workers, and for the U.S.-allied government in Afghanistan which is fighting its own Islamist insurgency.

POSSIBLE SUCCESSOR

Diplomatic sources told Reuters earlier on Friday that Karimov was dead, but it took several hours before an official announcement was made, in a statement issued by the Uzbek government and parliament.

That statement described Karimov as “truly great”. It said Prime Minister Shavkat Mirziyoyev was appointed head of the commission organising his burial.

Mirziyoyev was one of the people named by Central Asia analysts as a possible successor.

A 59-year-old former regional governor, he has been prime minister since 2003 and is personally in charge of agriculture, a major sector of the economy.

Opposition media reports say that in dealings with his own subordinates, Mirziyoyev can fly into a temper and will resort to swearing and curses to make his point.

Russian President Vladimir Putin expressed condolences to acting President Nigmatilla Yuldoshev. The Kremlin quoted Putin as saying his death was a “heavy loss for Uzbekistan”.

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Long criticised by the West and human rights groups, Karimov ruled Uzbekistan from 1989, first as the head of the local Communist Party and then as president of the newly independent republic from 1991 when the Soviet Union collapsed.

FUNERAL PREPARATIONS

In Samarkand, where Karimov’s mother and two brothers are also buried, public workers were already out on Thursday cleaning the streets, prompting speculation about an imminent state funeral.

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Samarkand airport was declared closed on Saturday for arriving and departing aircraft except those with a special permission, indicating that the government was making way for official foreign delegations to arrive.

Apart from Mirziyoyev, his deputy, Rustam Azimov, has also been seen as a possible successor. Security service chief Rustam Inoyatov and Karimova-Tillyaeva, the younger of Karimov’s two daughters, could become kingmakers.

According to the constitution, Yuldoshev is supposed to take over and elections must take place within three months. However, analysts do not consider Yuldoshev a serious player.

Whoever succeeds Karimov will need to perform a careful balancing act between the West, Russia and China, which all vie for influence in the resource-rich Central Asian region.

Another task for the new leader will be resolving tensions with ex-Soviet bloc neighbours Kyrgyzstan and Tajikistan over disputed borders and the use of common resources such as water.