SAN'A, Yemen -- Authorities arrested four al-Qaida members Saturday who were believed to be planning to carry out attacks in the capital, San'a, Yemen's interior minister said.

Interior Minister Rashad Rashad al-Eleimi said the suspects also had links to the four suicide bombers who had planned to blow Yemeni oil installations on Friday but were killed as the attack was foiled.

Security forces confiscated 12 bags each containing 88 to 110 pounds of highly explosive material as well as masks and women's clothing, which militants sometimes use to disguise themselves.

The arrests were made Saturday morning after an hours-long standoff that began Friday night when security forces surrounded the militants. The interior minister said the alleged militants opened fire at the security forces but nobody was hurt.

"We are certain that this cell has links with the al-Qaida network and with those who carried out the attacks in Mareb and Hadarmut," al-Eleimi told reporters, referring to the areas targeted Friday.

The violence coincided with an election campaign in which President Ali Abdullah Saleh, facing his first real challenge since he became head of state in 1978, has been reaching out to the country's most strident Islamic movement.

No group claimed responsibility for Friday's attacks. But Prime Minister Abdul-Kader Bajammal had said "investigators have uncovered all the details related to the two operations and the identity of the perpetrators," according to the official news agency.

He did not elaborate, but said work at the oil installations was proceeding normally.

There have been fears of an al-Qaida attack since 23 members of the terror network tunneled out of a Yemeni jail in February with help from prison guards. Fourteen prisoners remain at large.

Al-Qaida has an active presence in Yemen, the ancestral home of Osama bin Laden. Al-Qaida has been blamed for two attacks on ships off Yemen -- the bombing of the USS Cole that killed 17 American sailors in 2000 and the attack on a French oil tanker that killed one person two years later.

After the Cole bombing and the Sept. 11 attacks in the United States, the West began pressuring Yemen to join the war against terror. Saleh launched several crackdowns against extremists, winning praise from the United States.

Analysts said Friday's violence has al-Qaida's fingerprints, especially since it came after a videotape aired Monday of the network's No. 2, Ayman al-Zawahri, threatening attacks on the Gulf and on facilities he blamed for stealing Muslim oil.