Yemen's president, hospitalized in Saudi Arabia after an attack nearly a month ago on his palace, has instructed his deputy to hold talks with political opponents on a Gulf-sponsored plan for a transition of power. The country's main opposition coalition, however, dismissed the announcement.

Foreign Minister Abu Bakr al-Qirbi said Wednesday on Yemeni state television that he had visited President Ali Abdullah Saleh in the hospital. He said the two had discussed the Gulf initiative and the country's political crisis.

The U.S.-backed plan calls for Mr. Saleh to give up power in exchange for immunity from prosecution. The Yemeni president has agreed to the deal three times in recent months, refusing at the last minute each time to sign an accord.

Opposition spokesman Mohammed Qahtan said the country's dire economic and security situation does not allow for more meetings and negotiations. He said Mr. Saleh should immediately transfer power before any dialogue can take place.

Yemeni officials had said Mr. Saleh would make his first public appearance since the palace attack this week, but Wednesday they said that plan was delayed on the advice of his doctors.

Tens of thousands of Yemenis demonstrated Wednesday in the capital, Sana'a, and six other major cities demanding Mr. Saleh's ouster.

Protest organizers reported that about 320 members of Yemen's security forces defected to the opposition, including 150 from the elite Republican Guards led by Mr. Saleh's son Ahmed. Government officials have not confirmed the mutiny.

A series of defections by security forces have taken place since anti-government protests began in February. Most prominent was that of Brigadier General Ali Mohsen, who switched sides in March and has since sent his troops to guard protesters in Sana'a.

Also Wednesday, military officials said at least 26 soldiers and 14 Islamist militants were killed in heavy fighting in the southern city of Zinjibar as the two sides battled for control of a stadium on the outskirts of the city.

The clashes were part of daily government attacks on al-Qaida linked militants who have seized control of several areas in Abyan province, including Zinjibar and several smaller towns. Earlier, Yemeni army jets mistakenly bombed a passenger bus in the area, killing four civilians and wounding 12 others.

Yemen, the poorest Arab state, has also been shaken by a resurgent wing of al-Qaida and a separatist rebellion in the south. The United States and Saudi Arabia fear al-Qaida may use the chaos to launch attacks in the region and beyond.