Polls have closed in the presidential election in Yemen, with reports indicating high turnout in many areas despite calls for a boycott from the opposition and deadly violence in the south.

As the only candidate in the race, Abd-Rabbou Mansour Hadi, the vice-president, is set to take power, ending the 33-year rule of Ali Abdullah Saleh.

The Reuters news agency quoted an official from the election security committee as estimating a turnout of 80 per cent in Tuesday's vote, although final results will not be known for several days.

Turnout was likely to be lower in the south, where the boycott call and security concerns kept many at home.

Southerners, who accuse the north of grabbing their resources and discriminating against them, are demanding a divorce from the north with which they fought a civil war in 1994 after political union in 1990.

The Election Commission said in a statement that voting was halted in nine southern electoral districts, out of a national total of 301, because of the chaos.

Khamis al-Dayani, an election committee official, said nine of up to 300 polling areas in the country had experienced severe disruption.

'Qualitative leap'

Hadi cast his vote at a polling station near his house in the capital, Sanaa. The station was changed at the last minute because of reports of a bomb threat.

"This is a qualitative leap for modern Yemen," he said after voting.

"There will be big political, economic and social change, which is the way out of the crisis that has ravaged the country."

However, Saleh, who over the years has built a strong web of tribal and family relations, could still hold considerable sway after Hadi is installed.

Despite the vote's predetermined result, voting was brisk in Sanaa and some other cities, prompting election officials to keep the polls open two extra hours.

Long queues formed early in the morning outside polling stations in Sanaa amid tight security.

Yemen has more than 10 million registered voters, in a population of 24.7 million, according to the latest census.

Voters dipped their thumbs in ink and stamped their finger print on a ballot paper bearing a picture of Hadi and a map of Yemen in the colours of the rainbow.

"We are now declaring the end of the Ali Abdullah Saleh era and will build a new Yemen," Tawakul Karman, the prominent Yemeni human rights activist and Nobel Peace Prize winner, said as she waited to cast her ballot outside a Sanaa university faculty.

Elsewhere in Yemen, security forces fired on protesters throwing stones during an anti-election rally in front of a polling station in al-Hota, the capital of the southern Lahej province, killing two, witnesses and local officials said.

In Makala, another southern city, at least 16 people were injured in clashes between security forces and people opposed to the election.

An explosion struck a voting centre in the southern port city of Aden on the eve of the vote.

Streets deserted

The streets of Aden were nearly deserted and intermittent gunfire could be heard. Masked youths carrying rifles and machine guns patrolled junctions, preventing people from reaching polling stations.

Abdel-Aziz Yehiya, the election commission head in Aden province, said voting had gone well in most places, but that unknown armed men had seized 44 ballot boxes out of some 800 total.

After polls closed, Victoria Nuland, the US state department spokeswoman, congratulated the Yemeni people for "carrying out this successful presidential election and taking the next step in their democratic transition".

However, she said, the election was "only the first step in a long, complex transition" including constitutional and voting system reforms.

The UN special envoy to Yemen, Jamal Benomar, called on all parties in the country to abide by the Gulf Co-operation Council (GCC)-brokered power transfer deal.

"The international community and the United Nations Security Council would closely monitor this process," he said in Sanaa.

As part of the US -backed deal brokered by Yemen's Gulf neighbours, Saleh is stepping down in exchange for a blanket immunity from prosecution.

Saleh is now in the US for medical treatment after an attack on his palace in June left him badly burned, and hastened his descent from power.