Thousands of Uzbeks have lined Tashkent's main thoroughfare at dawn as President Islam Karimov's funeral cortege made its way through the city.

Karimov, who died on Friday at the age of 78 after suffering a stroke, will be buried later on Saturday in his hometown of Samarkand, about 300km southwest of the capital.

The veteran leader had run the ex-Soviet Central Asian nation since 1989 and nearly half of its 32 million citizens were born after he came to power.

Many mourners held flowers, mostly red roses, which they laid on the road as the funeral train, which set out at 6am local time on Saturday drove by on its way to the airport.

"What are we going to do without you?" a weeping mourner shouted.

A 39-year-old Tashkent resident who declined to be identified said: "This was the longest and hardest week in my life ... Still can't believe it happened. Don't know what happens now, I am lost."

"Only as the cortege drove by I realised who we had lost," said Usmon, 55, a teacher.
"I am in deep grief."

Prime Minister Shavkat Mirziyoyev has been designated mourner-in-chief at Karimov's funeral, which is seen as a strong hint he might become the next president.

Karimov 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.

If they fail to agree on a compromise, however, open confrontation could destabilise the mainly Muslim state that 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 would have repercussions for Russia, the regional power and home to hundreds of thousands of Uzbek migrant workers, and for the US-allied government in Afghanistan which is fighting its own Islamist insurgency.