ADEN/SANAA: An explosion tore through a polling station and gunfire nearby killed a soldier in Yemen Monday, the eve of a presidential vote to replace Ali Abdullah Saleh after a year of mass protests and spreading anarchy.

A spate of violence in south and east Yemen underlined the challenges Saleh’s successor will face as he seeks to prevent the country sinking further into chaos.

Interior Minister Abdul-Qader Qahtan said in the capital Sanaa that security measures were in place but some violence in the southern province of Abyan, a stronghold of Al-Qaeda militants, was unavoidable.

“There are preventive security measures to confront any contingency ... to confront any group that may attack people,” Qahtan told a news conference. “Abyan still has many districts under the control of Al-Qaeda. There are security failures ... and an explosion here and there is expected.”

The polling station blast in Aden caused no casualties but one soldier was killed and another injured when unidentified gunmen opened fire on an army patrol in the vicinity. It was unclear if the two incidents were related.

Southern separatists seeking to revive a socialist state that Saleh united with the north in 1990 oppose Tuesday’s vote, which has been touted by diplomats as a turning point for the country following a year of political upheaval.

In another southern province, Dalea, troops opened fire on an anti-election protest march, killing one protester and wounding nine, a leader of the Southern Movement said.

A local official said the march was unauthorized and protesters had shot at soldiers, wounding one.

Southern activists, who accuse the north of taking their resources and discriminating against them, have said they will boycott the election because they want no part in a process organized across both halves of the country.

Residents of Dalea said armed secessionists had set up checkpoints on the main roads to prevent ballot boxes from being delivered to polling stations. Militants linked to Al-Qaeda have also exploited weak central government control to expand their foothold in the south, seizing several towns over the past year.

Unidentified gunmen attacked a polling station in the city of Sayoun in the eastern province of Hadramawt, besieging it for several hours until security reinforcements arrived to disperse them, killing one and arresting two in the ensuing clashes, a local official said.

Security forces also arrested three suspected Al-Qaeda militants who were preparing explosive material in a residential quarter of the town of Al-Khadra in the southern Lahej governorate, an official said.

Militants in the town of Lawdar in Abyan province, which borders Lahej, ambushed and killed two pro-government tribesmen, a tribal source said.

In what was likely his last speech as president, Saleh urged Yemenis to go to the polls and vote for Vice President Abed Rabbou Mansour Hadi, the only candidate in the election, as laid out in a power transfer deal brokered by Yemen’s neighbors.

“This event comes within the framework of implementing what we adopted for the sake of a peaceful transition of power to lift our good country and steadfast people from the suffocating and bitter crisis which has lasted a whole year,” Saleh said.

The vote will make Saleh, now in the United States for further treatment of burns suffered in a June assassination attempt, the fourth Arab autocrat to leave office in a year after revolts in Tunisia, Egypt and Libya.

But prospects for stability remain uncertain given Saleh’s vow to return home to resume leadership of his party, a split in the military, Al-Qaeda militants entrenched in the south, a Houthi Shiite Muslim revolt in the north and the secessionist movement in the south.

In a speech late Monday, Hadi said Yemen had returned from the brink of collapse and called on the splintered military to help unify the Arabian Peninsula state, where chaos would threaten nearby oil shipping lanes crucial to world economy.

“In the past months Yemen has passed through unprecedented hardship, to the point where the most optimistic of observers expected it to become as fragmented, splintered and destroyed as Somalia,” Hadi said. “We cannot talk about stability without returning life to a natural state and removing the phenomena which have appeared, beginning with the split in the army.”