During a speech at the White House, Mr Bush said US agents had scuppered al-Qaeda plots to cause carnage in America, Africa, London and Pakistan.
He said the thwarted plots included a plan to blow up an explosives-laden water tanker to target US Marines in Djibouti, new airliner suicide strikes in the US and Britain and a bid to sow biological carnage with anthrax, he said.
Mr Bush also defended the practice of covertly holding prisoners overseas, as well as "tough" interrogation procedures that some critics have denounced as torture.
"It has been necessary to move these individuals to an environment where they can be held in secret, questioned by experts and, when appropriate, prosecuted for terrorist acts," he said.
Mr Bush said he could not describe the methods used because it might help terrorists learn to resist. "But I can say the procedures were tough, and they were safe, and lawful, and necessary."
"I'm going to share with you some of the examples provided by our intelligence community of how this program has saved lives," he said.
Intelligence gathered
He said the first big break in smashing al-Qaeda after the September 11 in 2001, came with the capture in 2002 of Abu Zubaydah, a key aide to Osama bin Laden, who ran Afghan terror camps.
Severely wounded Zubaydah, nursed back to health by US medics, was "defiant and evasive" and declared he hated America, Mr Bush said.
Even so, he spilled "nominal" information, President Bush claimed, including a "vital piece of the puzzle" that Khalid Sheikh Mohammed (KSM) was the "brains" behind September 11.
Agents used intelligence extracted by Zubaydah, to crack a previously unknown plot to stop "a terrorist attack being planned for inside the United States," and arrested one plotter en route to America, Mr Bush said.
Once Zubaydah clammed up, US agents were forced to use what he termed an "alternative set of procedures," which nevertheless complied with US laws, the constitution and US treaty obligations, he said.
Mr Bush did not outline the methods -- but critics have claimed CIA agents used techniques tantamount to torture like water-boarding -- simulated drowning -- and exposed prisoners to extremes of temperature and sensory deprivation.
"Soon, he began to provide information on key al-Qaeda operatives," Mr Bush said, including another presumed September 11 plotter, Ramzi bin al-Shibh, and KSM, later captured in Pakistan in 2003 and subjected to CIA methods, Mr Bush said.
Mohammed spilled the name of other al-Qaeda operatives, and intelligence which also led to the capture of Hambali, leader of the Southeast Asian terror group Jemaah Islamiya (JI), who was implicated in the 2002 Bali nightclub bombings, which killed more than 200 people.
Mr Bush added that after Hambali's arrest, believed to have been in Thailand in August 2003, KSM implicated Hambali's brother, a JI cell leader in Pakistan, who was himself to expose another cell of 17 southeast Asian terrorists.
"(The) operatives were being groomed at KSM's request for attacks inside the United States, probably using airplanes," Mr Bush said.
"During questioning, KSM also provided many details of other plots to kill innocent Americans."
President Bush said the planned attacks included an idea to plant bombs in US buildings high enough up to stop people on upper floors escaping.
Information was also prised from Mohammed on al-Qaeda's biological weapons quest and he also exposed a cell used by the terror group to produce anthrax, a deadly biological agent.
Terrorists in CIA custody also provided information that helped stop a planned strike on US Marines in Djibouti using an explosives-laden water tanker, Mr Bush said.
"They helped stop a planned attack in Karachi using car bombs and motorcycle bombs and they helped stop a plot to hijack passenger planes and fly them into Heathrow or the Canary Wharf in London."
Though he laid out the chain of apparently inter-linked terror plans, President Bush did not give exact dates for planned attacks, names of all perpetrators or say how developed the plots were when they were thwarted.
But he maintained the CIA programs had provided information from initial leads to photo identifications and precise locations of where terrorists were hiding.
"This (CIA) program has helped us to take potential mass murderers off the street before they are able to kill,” Mr Bush said.
Suspect transferred
President Bush also announced that Khalid Sheikh Mohammed and 13 other top al-Qaeda suspects had been transferred to the Guantanamo Bay camp in Cuba, to be tried by military commissions that must be approved by the US Congress.
"As soon as Congress acts to authorise the military commissions I have proposed, the men our intelligence officials believe orchestrated the deaths of nearly 3,000 Americans on September 11, 2001 can face justice," he said.
Mr Bush said that the International Committee of the Red Cross will have access to suspects, and the detainees, in turn, will have access to legal counsel. He stressed that "they will be presumed innocent."
The international Red Cross later said that it will have access to 14 terror suspects, including the self-proclaimed architect of the September 11, 2001 attacks, that the United States is transferring to Guantanamo Bay detention centre.
"We have had confirmation that we will be able to visit them in Guantanamo Bay," said Antonella Notari, a spokeswoman for the International Committee of the Red Cross.
The ICRC has been the only agency allowed to carry out confidential checks on conditions for detainees held at Guantanamo Bay, Cuba, under its internationally-recognised role as the guardian of the Geneva Conventions.
With the transfer of the suspects, Mr Bush said the secret CIA program now holds no prisoners but will be kept operational in order to continue to detain and interrogate suspected extremists captured in the war on terrorism.
The US president acknowledged that the CIA prisons and the detentions at Guantanamo had in some cases soured US relations with key allies.
"I want to be absolutely clear with our people and the world: The United States does not torture. It's against our laws and it's against our values. I have not authorised it and I will not authorise it," he stressed.
He also rejected calls to shut down the Guantanamo detention centre.
Mr Bush was giving the third of a series of speeches on the war on terrorism ahead of critical November US legislative elections, which some in his party fear will be dominated by the unpopular war in Iraq.