ADEN, Yemen - Yemen said on Monday its security forces had foiled a planned al-Qaida attack in the southern province of Aden.

Separately, a ruling party leader said the first speech by President Ali Abdullah Saleh since he was taken to Saudi Arabia for treatment after a bombing was expected to be carried by Yemeni state television on Tuesday.

The state news agency Saba quoted a security source as saying six people "among some of the most dangerous elements" of al-Qaida were captured while trying to enter the province, which is the location of a port and an oil refinery.

The report said they planned to attack "vital and economic installations", giving no further details.

Yasser al-Yamani, a leader of Saleh's ruling General People's Congress, told Al Arabiya television that Saleh's speech was expected to be aired by state television on Tuesday, but signaled the president was unlikely to offer to end his three decades of rule.

"The president is the legal and constitutional president of Yemen according to elections," Yamani said.

Yemeni officials had said on Sunday that Saleh, not seen in public since an attack on his palace in early June, was well enough to soon return to Yemen and would make a media appearance within the following couple of days.

Speculation about Saleh's health and the likelihood of his return to Yemen have been rife since he was hurt when a bomb went off on June 3 in a mosque in his presidential palace.

The president has not been seen in public since the explosion, which killed several people and wounded the prime minister, two deputy prime ministers and the speakers of both parliamentary chambers. It is not clear what role if any Saleh, under pressure to step down, sees for himself in ruling Yemen. Yemen has been rocked by months of protests against Saleh. Before that he was grappling with a rebellion in the north, separatist violence in the south and a resurgent wing of al-Qaida.

Months of protests requesting Saleh to step down have brought chaos to Yemen, which is home to al-Qaida's potent regional wing.

The Yemeni army has been battling hundreds of Islamist militants affiliated to al-Qaida who seized control of the southern city of Zinjibar and smaller towns in the province of Abyan. The United States and Saudi Arabia fear that al-Qaida will exploit the country's chaos to launch attacks.

The security source said the arrested militants, all bomb experts, carried detonators and communications equipment.

The state news agency Saba, which frequently plays up the threat from al-Qaida, gave no further details and the report could not been independently verified.

Saba said five al-Qaida militants had been killed and seven Yemeni soldiers were injured in clashes in Abyan.

Opponents of Saleh say the president let his forces hand over control of Zinjibar to militants in order to stoke fears that only his rule could prevent an Islamist takeover.