ALMATY (Reuters) - Senior Uzbek officials failed to show up at an Independence Day event on Thursday, leaving foreign diplomats guessing who was running the country while its long-time ruler is gravely ill.

President Islam Karimov, 78, who has no obvious successor, suffered a brain hemorrhage at the weekend, according to his daughter. He did not deliver an annual holiday address on Wednesday for the first time in 25 years.

The government has made no statements since saying on Sunday Karimov was in hospital and has not identified any acting head of state. Official media have also carefully avoided singling out any of the senior officials as the person in charge.

Diplomats had hoped to get a clearer picture from senior officials at the event on Thursday, which is traditionally attended by the foreign minister and sometimes deputy prime ministers.

But none of them turned up, a person who was present told Reuters, a move that could indicate a power vacuum has paralyzed decision-making. The highest-ranking official present was a deputy foreign minister.

Karimov has ruled Uzbekistan, which is rich in energy and minerals, in an authoritarian style since 1989, first as a Communist leader then as president after the Soviet Union fell in 1991.

He has presented himself as a bulwark of stability in a country situated on the northern borders of Afghanistan. Critics have accused him of using the Islamist threat as an excuse to crack down on any kind of dissent.

Kazakh political analyst Dosym Satpayev said key players, such as Karimov family members and top government and security officials, were likely still in talks about succession.

"It seems they haven't arrived at a compromise yet," Satpayev said. "I think they will do that eventually. If the vacuum persists for too long, there will of course be nervousness among the population."

(Reporting by Olzhas Auyezov; Editing by Angus MacSwan)