Violence in southern Yemen has marred an election to replace veteran leader Ali Abdullah Saleh.

At least six people have been killed in incidents at southern polling stations despite a large army presence, after separatists called for a voter boycott.

But voting in the capital Sanaa was peaceful as people formed orderly queues from the early morning.

Voters are expected to rubber-stamp Vice-President Abdrabbuh Mansour Hadi - the only candidate in Tuesday's poll.

Officials told BBC Arabic that gunmen killed four soldiers in an attack on a polling station in Hadramawt province.

Two soldiers were also killed in an attack in the al-Hawta district, and there was violence reported in Aden, the main city in the south.

The separatist Southern Movement has called for a day of "civil disobedience" to mark the vote.

The poll comes after a year of violent anti-government protests in the Arabian Peninsula's poorest country.

'End of Saleh era'

The BBC's Rupert Wingfield-Hayes, in Sanaa, says the situation there is peaceful, and there is a lot of enthusiasm at the prospect of getting rid of the old president.

The main supporters of the uprising that began in January 2011 are backing Mr Hadi, whose election posters are prominently displayed in Sanaa.

He is from the south himself and has called for dialogue with the separatists.

Yemeni human rights activist Tawakkol Karman, joint winner of the 2011 Nobel Peace Prize, said as she voted that the election marked the end of President Saleh's 33-year long reign.

"Today we are building the new Yemen, we are building the democratic and happy Yemen that all of the youth and women have dreamed about," she said.

But the country still faces multiple challenges - an ongoing rebellion in large chunks of the country, al-Qaeda militants, widespread malnutrition among children and severe drought.

Husam Al-Sharjabi, a 37-year-old protester who recently formed the al-Watan opposition party, acknowledged in a BBC interview that al-Qaeda posed a real threat.

"It's a threat that has been exaggerated, but it must be taken seriously," he said.

"We need to take a multi-faceted approach involving defence, diplomacy and development, to minimise the opportunities for these groups to recruit from the poor and disenfranchised."

The election follows a deal brokered by Yemen's Gulf Arab neighbours.

Mr Saleh, who has been in office for 33 years, signed the agreement to step down - but only once a new president has been elected.

On Monday, he urged Yemenis to vote for Mr Hadi to ensure "a peaceful transition of power".

According to the election rules, there is no minimum turnout for the vote to be valid.

If only one person turns out to vote for him, Mr Hadi will still win.

More than 12 million people are eligible to vote. Ten million registered for the last vote in 2006 in addition to 2.2 million new voters.

The new president is due to stay stay in office for two years, when a further round of presidential and parliamentary elections are scheduled.

Source;bbc