Azerbaijan's Central Election Commission says 97% of voters have approved a series of amendments to the country's constitution.

There is an unheard-of level of falsification going on

Arif Gadzhiyev Opposition leader

The referendum was seen by critics as paving the way for the ageing president, Heydar Aliyev, to hand over power to his son.

With most votes counted, the commission said 88% of the population had turned up at polling stations, greatly exceeding the number required to validate the referendum.

However, opposition leaders say dozens of their observers were barred from polling stations across the country and that others had seen numerous violations.

'Unsure' voters

The opposition leaders said election officials had been bussing voters around polling stations to increase the vote and that ballot boxes had been sealed on Friday night before the referendum began.

Other reports said many of the country's 4.4 million registered voters planned to stay at home because they did not understand what they were voting for.

Heydar Aliyev

One of the last members of the former USSR's Politbureau to retain political power Aged 79 and suffers from a heart condition Denies plans for heir but appears on political posters side-by-side with son Ilham

Monitors from the main opposition party, Musavat, said that in one town only eight people had cast their ballots out of a population of 7,000 people.

Election commission figures show a turnout of over 50% for the same town, Nardaran.

"There is an unheard-of level of falsification going on," said Musavat's secretary-general, Arif Gadzhiyev.

"We have recorded violations at every polling station in the country."

Well-groomed son

The government in the oil-rich ex-Soviet republic denied vote-rigging allegations and said the changes to the constitution were need to bring Azerbaijan in line with other democracies.

The proposed changes to the decade-old constitution reflected how far democracy has come in the country, officials said.

The president's son already holds senior posts

The changes include amendments to the human rights code, such as the introduction of alternative service for military recruits.

But many critics believe the referendum is a ruse to make it easier for the president to hand over power to his son.

If Mr Aliyev became ill, the amended constitution would allow him to hand the running of the country to the prime minister - who is directly appointed by the president - until elections are called.

Currently, the speaker of parliament, elected by parliamentary vote, takes over if the president falls ill.

The opposition says it would be a simple step for the ailing Mr Aliyev to make his son, Ilham, prime minister.

Ilham Aliyev is already vice-president of the ruling party, deputy head of the State Oil Company and director of Azerbaijan's Olympic Committee, as well as being Azerbaijan's representative at the Council of Europe.

Mr Aliyev, a former KGB officer, has faced strong opposition in Azerbaijan for his authoritarian style of leadership.

Tensions with the opposition have frequently led to demonstrations, brutally repressed by police.