He returned last week, 18 months after he escaped from Baghdad. He is one of the highest-ranking officers ever to defect from the Iraqi regime.
"Saddam Hussein thought I was conspiring against him and, though he had no firm evidence, his feeling was right," he says.
Interrogated twice, General Sammara'i fled to Kurdistan with his family, bringing to the Western world the first detailed evidence that Iraq had been systematically deceiving the United Nations about its weapons of mass destruction.
His claim that President Saddam had a programme to manufacture anthrax and other biological and chemical weapons was later confirmed by Iraq to UN inspectors.
Sitting in an office overlooking Park Lane, General Sammara'i, a short, thick-set man of 49, told the Independent that he thought Dr Rolf Ekeus, leader of the UN team supervising the destruction of Iraq's weapons, had made a mistake earlier this week in saying that Iraq may still be concealing between six and sixteen long-range missiles.
"I believe Saddam has 40 missiles," he says. "He also has 255 containers of biological agents. In 230, the agent is in powder form, which has no expiry date, and in 25, it is in liquid form, which will deteriorate."
He says he is 100 per cent positive of the information, which came from an informant close to Qusai, the President's second son who is in overall charge of Iraq's multitude of security agencies.
General Sammara'i believes Iraq also had a hand in the bombing at Dhahran, Saudi Arabia, last week in which 19 Americans were killed.
He says that in September 1990, just after the invasion of Kuwait, he was a member of an Iraqi committee in charge of sabotage operations against the allied forces which were massing in Saudi Arabia.
He said that the committee, which was never dissolved, considered bombing the residential buildings of the United States and other foreign military in Saudi Arabia.
The evidence of defectors is always suspect, because of the temptation to exaggerate. In a society as secretive as Iraq, stories are hard to check. But as head of military intelligence, General Sammara'i was in a position to know most of the secrets of the regime and his previous revelations about its biological and missile programmes have been largely confirmed by other sources.
In his account of his years in Iraqi intelligence, the main surprise is that he survived at all.
Born in the city of Sammara'i, 70 miles north of Baghdad, in 1947, he joined the army when he was 18 and military intelligence in 1971. But it was during the Iran-Iraq war that his career prospered.
He says: "We in military intelligence were very capable and we were never taken by surprise in 85 battles."
It is typical of the regime that as he was promoted, he was regarded with increasing suspicion. He says: "The regime did not trust me, because I had extensive contacts with the Kurds. From 1984, I was followed, but they needed me."
General Sammara'i says that he was briefly demoted but brought back after the success of an Iranian surprise attack at Fao in south Iraq in 1986.
The one piece of information he denies having had advance knowledge of was the decision to attack Kuwait in 1990.
In the aftermath of invasion, Saddam Hussein, apparently taken by surprise by the allied reaction, put him in charge of intelligence in Kuwait. But "they felt the way I was reporting things proved that I disapproved [of their policies]."
He was brought into the presidential palace, a move which he says was aimed at reducing his real authority. Believing the President had decided to kill him, he planned his escape to Iraqi Kurdistan.
General Sammara'i does not believe that a military coup in Iraq stands much chance of success. The grip of President Saddam and the intelligence services is too tight.
His own proposal is for the opposition, in association with the Kurds, to start military operations against President Saddam and look for massive defections from the Iraqi army.
In March 1995, he tried to carry out this strategy with some success.
General Sammara'i is notconfident that the latest round of in-fighting within Saddam Hussein's family will bring down the regime, nor does he expect the quarrels to stop.
He says that Saddam's son, Uday, does not have any real power and that the family feuds do not necessarily weaken the President's hold on power.
On leaving Kurdistan last year General Sammara'i moved to Damascus, where he is completing a book on his experiences in Iraq.
Of the future he says: "Saddam will definitely take revenge on the people who threatened his leadership."
As for the Scud missiles and the biological weapons: "He wouldn't have got them if he didn't intend to use them."