TUNIS (Reuters) - President Zine al-Abidine Ben Ali has won a fifth term with 89.62 percent of the vote in Tunisia's presidential election, officials announced on Monday.

One opposition party called Sunday's vote a missed opportunity to make the North African country more democratic, echoing accusations by international human rights groups that the campaign took place in an atmosphere of repression.

Ben Ali, who is 73 and has been in power for 22 years, has rejected those allegations and warned that anyone spreading lies to damage the country's image will be prosecuted.

"It is a matter of pride that the results have confirmed the people's support for President Ben Ali and their trust in him," Interior Minister Rafik Bel Haj Kacem, who oversaw the election, told a news conference at his ministry.

He was interrupted several times by female ministry employees clapping, ululating, and shouting "Long live Ben Ali!"

Many voters credit the president with turning Tunisia, which attracts millions of foreign tourists each summer, into a stable and relatively prosperous country in a region that suffers from poverty and political turmoil.

His winning margin was down slightly compared with the 94.4 percent he received in the last election five years ago, a dip seen in Tunis as possibly helping to deflect foreign criticism that the latest race was tilted in his favour.

Ben Ali has established Tunisia as a moderate voice in the Arab world and Western governments view it as a bulwark against Islamist extremism -- though some have reservations about its record on democracy.

"MEANINGLESS VOTE"

Tunisia's most prominent opposition figures did not take part in the election. Two of Ben Ali's challengers on the ballot rarely criticise the president and the third acknowledged during the campaign that he could not win.

"The regime has missed another opportunity to carry out a democratic transition in Tunisia," said Rachid Kechana, deputy Secretary-General of the opposition PDP party, which boycotted the election.

"The election was meaningless and the results confirm that," he told Reuters.

Tunisia is especially sensitive to criticism of its democracy record because it is expected to apply to the European Union next year for "advanced status" -- which could give it preferential trade terms and boost its international standing.

The Tunisian president came to power in 1987 when doctors declared his predecessor, Habib Bourguiba, unfit to rule after more than 30 years in power.

Almost all voters who spoke to Reuters reporters on polling day said they had backed Ben Ali.

"He is the saviour of our country," said 50-year-old Nejia Azouzi as she cast her ballot in the capital on Sunday.

Ben Ali's RCD ruling party won 161 seats in the 214-seat parliament in a legislative vote that was held simultaneously on Sunday, officials said.