Rival security forces clash in Yemeni capital, two killed

Women attend a demonstration to demand the ouster of Yemen's President Ali Abdullah Saleh in the southern city of Taiz April 12, 2011.

SANAA (Reuters) - Rival Yemeni forces clashed in the capital Sanaa on Wednesday, killing two people, and the opposition awaited clarification from Gulf Arab mediators on the timeframe for a proposed transfer of the president's powers.

Clashes also erupted in the southern city of Aden when security forces tried to break up a protest march demanding an immediate end to President Ali Abdullah Saleh's 32-year rule, witnesses said.

Gulf Arab foreign ministers have said they would invite Saleh and his opponents to mediation talks on a transfer of power for the Arabian Peninsula state to end a standoff after two months of street protests.

The opposition initially rejected the plan, but they met ambassadors of Saudi Arabia, Kuwait and Oman on Tuesday to seek clarification on the Gulf mediators' understanding of a proposed "transfer of power".

Opposition sources said they were expecting an answer from the Gulf on Wednesday on the timeframe and details of the plan, and could respond immediately. An opposition source has said talks could start as early as Saturday in Riyadh.

In Sanaa, tension remained high near the encampment of a defected army general, Ali Mohsen, whose forces are protecting thousands of anti-Saleh protesters in their tent camp near Sanaa University.

"Central security forces clashed with the forces of the first armoured division, and two troops were killed outright while four more are in a critical condition," a military source said. One of the dead was from Mohsen's forces while the other was from the government side.

A source close to Mohsen's forces said pro-Saleh security forces had fired rocket-propelled grenades and assault rifles at their forces after they set up a checkpoint on a road leading to the protest zone.

Mohsen's forces returned fire and battled the pro-government forces for an hour before Saleh's forces retreated, leaving the checkpoint intact, the source close to Mohsen said.

The situation could escalate into more violence in the heavily armed but impoverished Arabian Peninsula state, where half the 23 million people own a gun.

Further south, at least one person was killed in the southern port town of Aden when police fired shots to stop protesters marching from one district of Aden to another and who hurled rocks at police as they tried to clear makeshift roadblocks, residents said.

Sporadic gunfire continued across the city and security forces, some in armoured vehicles and others with water cannon, were deployed throughout.

South Yemenis, who complain of marginalisation after a civil war with the north led by Saleh in 1994, insist any deal must give them a say in government.

(Reporting by Mohammed Ghobari in Sanaa and Mohammed Mukhashaf in Aden; Writing by Cynthia Johnston; Editing by Janet Lawrence)