Ghailani, who had a $25 million reward on his head, was arrested Sunday in the eastern city of Gujrat along with 15 others after a 12-hour shootout with police and intelligence agents.
"This is a big success," Interior Minister Faisal Saleh Hayyat told Pakistan's Geo television network. Ghailani was being cooperative and had told authorities "very valuable" information, said Hayyat.
"It would be premature to say anything about this, but obviously we have certain information, some very valuable and useful leads have been acquired," he said.
Ghailani, who is said to be in his 30s, currently is being held at an undisclosed location, but Hayyat suggested that he might be turned over to U.S. authorities soon.
The United States wanted Ghailani for his alleged role in the 1998 dual bombings of U.S. embassies in Kenya and Tanzania. The bombings killed over 200 people, including 12 Americans.
The FBI and Justice Department also asked for help over the summer in finding Ghailani and seven other al-Qaida suspects so as to avoid a possible terror attack in the United States.
U.S. authorities suspect him of buying the truck used to bomb the U.S. Embassy in Dar es Salamm, Tanzania. Ghailani, who also calls himself "Foopie," "Fupi" and "Ahmed the Tanzanian," was indicted on Dec. 16, 1998 in the Southern District of New York for his alleged role in the bombings.
If convicted Ghailani could face the death penalty on charges of murder of U.S. nationals outside the United States, conspiracy to murder U.S. nationals outside the United States, and attack on a federal facility resulting in death.
The 15 other suspects arrested with Ghailani on Sunday are from Africa, but authorities have not said whether they also are connected to al-Qaida. Ghailani's wife also was arrested, as well as several children.
The authorities, who learned of Ghailani's whereabouts from a suspected Pakistani militant who was arrested earlier, also confiscated two AK-47 rifles, two computers, computer diskettes, plastic chemicals and a "large amount" of foreign currency at the arrest site.
To date, Pakistan has arrested more than 500 al-Qaida suspects from within its borders. Pakistan became an important backer of the United States in its war on terror after the Sept. 11, 2001 attacks in America.
The lists of arrests made in Pakistan include al-Qaida No. 3 leader Khalid Shaikh Mohammed. He was arrested in March 2003 during a raid in Rawalpindi. Two other top al-Qaida men, Ramzi Binalshibh and Abu Zubaydah, also were arrested in Pakistan.
Almost all of the foreign suspects were later handed over to the U.S. officials.
Al-Qaida head Osama bin Laden and key partner Ayman al-Zawahiri, are believed to be hiding in the rough terrain of the tribal frontier between Pakistan and Afghanistan, but officials have yet to pinpoint his location.