Gunmen attacked an office of Yemen's electoral committee in a southern province, a local official said on Sunday, in the latest sign of opposition to a presidential election next month.

The official told Reuters the gunmen, armed with machine guns and rocket-propelled grenades, wounded two soldiers who were guarding the building in Dalea, before fleeing the scene.

The government, weakened by a year of protests against outgoing President Ali Abdullah Saleh, faces challenges from al Qaeda-linked militants who have seized territory in the south and separatists who want to revive a southern socialist state that existed before Saleh united it with the north in 1990.

There have been frequent attacks on government forces and offices in the south, which officials have blamed on militants and separatists.

Hours after the attack on the electoral committee, troops in Dalea opened fire on a car carrying a leader of the separatist Southern Movement, Shalal Ali Shayea, wounding a journalist traveling with him, a group activist told Reuters.

The activist said it appeared that the car had failed to slow down as it approached a checkpoint.

Thousands protested on Friday against the election, some burning their voting cards and raising the flag of the old South Yemen.

The people of the south reject the elections completely, separatist leader Nasser al-Khubbagi told Reuters on Friday. Holding them is an affirmation of the (northern) occupation and legitimises its continuation in the south.

Separatist leaders have vowed that the resistance to the election would be non-violent in the south, which is home to many of Yemen's oil facilities and where many say northerners have seized resources and discriminated against them.

The Sanaa government says the south's economic woes are shared by the north.

The United States and Saudi Arabia fear Islamist militants are exploiting the turmoil to strengthen their foothold in the south, near oil shipping routes through the Red Sea.

Saleh, who travelled to the United States on Saturday for treatment for wounds sustained in an assassination attempt last year, has handed over power to his deputy following the protests against his rule, paving the way for the early presidential election on February 21.

Northern Shi'ite Muslims rebels known as Houthis, who have been left out of the deal to ease Saleh out of power, have said they planned to boycott the vote.

(Reporting by Mohammed Mukhashaf; Writing by Isabel Coles; Editing by Alessandra Rizzo)