Yemeni security forces have arrested two al-Qaeda members, including a local leader, during a raid in the southern province of Abyan, officials say.
Abdul Rauf Nassib and Egyptian Sayyed Imam Sherif were arrested with about a dozen other militants in the remote Lawder area, they said.
Troops backed by tanks and helicopters launched the raid on Wednesday.
The US is helping Yemen - which has suffered its own terror attacks - to track down militants.
Officials said security forces continued to surround a hideout where dozens of militants were believed to be sheltering near Lawder, 470km (290 miles) south of the capital, Sanaa.
The Yemeni opposition party al-Islah said the men had been given until Friday to "surrender unconditionally or face a military assault", the AFP news agency reported.
Mr Nassib is reported to have been Mohammad Hamdi al-Ahdal's bodyguard.
He is alleged to have helped 10 militants suspected of involvement in the bombing of the USS Cole off the coast of Yemen in October 2000, to escape from Aden prison in April 2003.
YEMEN WAR ON AL-QAEDA
Mar 2004: Abdul Rauf Nassib and Sayyed Imam Sherif among more than a dozen militants arrested
Jan 2004: Yemen announces detention of al-Qaeda suspect Jaber al-Baneh wanted by US
Nov 2003: Al-Qaeda leader Mohammed al-Ahdal arrested
Sept 2003: Riyadh bombing suspect Bandar al-Ghamdi arrested
Apr 2003: Al-Qaeda suspect Fawaz Yahya al-Rabeei arrested
Nov 2002: Six suspected al-Qaeda members killed in US missile strike
Last November, Mr Nassib was the sole survivor of a US missile attack on a car, which killed six suspected al-Qaeda members in eastern Yemen, officials said.
Sayyed Imam Sherif, who was also reportedly captured, founded the Egyptian Islamic Jihad group which al-Qaeda leader Osama Bin Laden's right-hand man, Ayman al-Zawahri, once led, according to the website of Yemen's ruling party, GPC.
Yemen has stepped up its operations against Islamic extremists since the 11 September 2001, attacks on the United States, allowing US forces to enter the country and train with its military.
The crackdown comes amid reports that terrorists are planning attacks in Yemen, where security has been tightened around foreign institutions and government buildings.