Algerians are voting in a presidential election which opposition groups have described as a charade. The incumbent, President Abdelaziz Bouteflika, is standing for a third term in office against five little-known opponents.

Observers say the 72-year-old is almost certain to be re-elected and many voters are likely to boycott the poll.

Opposition candidates include two nationalists, two moderate Islamists and a woman veteran left-winger.

But their posters are invisible in the capital, where the face of the incumbent adorns every available space, correspondents say.

Mr Bouteflika has promised to spend $150bn (£102bn) on development projects and create three million jobs, and stresses the fact that he has restored stability in Algeria.

The president has urged Algeria's 20 million registered voters to make the trip to polling stations, eager to enhance his authority by a high turnout.

But the BBC's Rana Jawad in Algiers says many people are simply sitting out the vote in the overwhelming conviction that Mr Bouteflika will win regardless of their ballot.

One voter, 26-year-old sport teacher Abdeljaleel Saad, told the BBC: "I will not vote. We already know the result, so what is the point?"

For those who are taking part in the poll, however, the incumbent is the clear favourite, adds our correspondent.

Nacer Djabi, a political analyst, told the Reuters news agency: "Voting or not will make no difference as Bouteflika will win anyway. This is why poor turnout is likely."

In November, the Algerian parliament rubber-stamped an amendment that would change the constitution, meaning Mr Bouteflika can now run an unlimited number of times - which analysts say virtually makes him president for life.

Mr Bouteflika wants to be seen as a leader above the political fray, a man who can unite all Algerians, and many do credit him with ending the civil war between the military-backed government and Islamic insurgents which lasted throughout the 1990s, says BBC Arab affairs analyst Magdi Abdelhadi.

  The conflict was triggered when the military intervened in a parliamentary poll in 1991 to stop an Islamist victory, leading to violence that left up to 150,000 people dead.

"I continue to regard the restoration of civil peace as a national priority, as long as hotbeds of tension and pockets of subversion survive," Mr Bouteflika said in his final campaign speech on Monday.

But critics of the post-colonial order in Algeria say real power does not come from the ballot box but from the military and security services who anoint the man they want to be president.

Mr Bouteflika is said to have curbed some of their influence although many still believe the levers of power remain in the hands of shadowy figures who are the de facto rulers of this vast and oil-rich country, our correspondent says, and that is why the opposition says the election is a charade.

Polling stations are due to close at 2000 local time (2000 BST).

Results of the ballot will be announced on Friday.

Turnout in 2004 was just under 60%.