Three soldiers were wounded in a clash with southern separatists near a polling booth in Lahij province on Sunday, two days ahead of Yemen's presidential election, a government official said.
"Gunmen from the Southern Movement attacked military vehicles carrying ballot boxes to a polling booth in a school" near Al-Anad air base in Lahij, the official told AFP. "Three soldiers were wounded in an exchange of fire."
A faction of the Southern Movement has called for a day of "civil disobedience" on Tuesday when Yemenis are to vote for Vice President Abdrabuh Mansur Hadi, the sole candidate, to replace outgoing President Ali Abdullah Saleh.
It urged supporters to rally in the main southern city of Aden on Monday to "demand the freedom and independence" of the south.
Other members of the Southern Movement, who say the poll fails to meet their aspirations for autonomy or southern independence, have been campaigning for a boycott.
On Friday, three civilians were wounded as southern militants traded fire with police outside a polling station, residents said.
Under a Gulf-sponsored accord signed in November, Hadi, himself a southerner, is standing as the sole candidate to replace Saleh.
Saleh, who has been receiving medical treatment in New York from bomb blast wounds at his Sanaa palace compound last June, agreed in November to a power-transition deal after months of mass protests demanding his ouster.
Yemeni authorities have mobilized more than 103,000 members of the security forces around the country to safeguard the polling, a member of the senior electoral commission in Sanaa said.