Pakistan has arrested a key suspect in the bombings of two US embassies in East Africa in 1998.
Ghailani was reportedly arrested after a fierce gun battle (Photo: FBI)
He has been named as Ahmed Khalfan Ghailani, an alleged al-Qaeda militant with a $5m American bounty on his head.
Pakistan Interior Minister Faisal Saleh Hayat said the Tanzanian was captured during a raid in a small town in central Pakistan on Sunday.
He was held with at least a dozen others after a shoot-out lasting several hours, the minister said.
His Uzbek wife and two South African nationals were among those arrested with him, Mr Hayat added.
Mr Ghailani has been indicted in the US over the bombings of the American embassies in Nairobi, Kenya, and Dar es Salaam, Tanzania, nearly six years ago.
More than 200 people were killed in the two explosions, including 12 American citizens. Most of the victims were Kenyans and Tanzanians.
Ghailani was arrested after a raid on this house
Mr Ghailani is on the FBI's list of 22 "most wanted terrorists".
A $5m reward had been offered by the US government for information leading directly to his arrest or conviction.
He is in his early 30s, and goes by the nicknames "Foopie" and "Ahmed the Tanzanian".
Mr Hayat said Mr Ghailani was at present in Pakistani custody and being interrogated, but did not rule out the possibility of him being handed over to the US at a later stage.
The interior minister said it took the authorities a few days to make a positive identification of Mr Ghailani, but it had now been established beyond any doubt that he was the person wanted by the FBI.
He described the arrest as "a phenomenal success" in Pakistan's efforts to wipe out al-Qaeda suspects and other Islamic militants in the country.
"He is alleged to be one of the key figures in the bombings... on the US embassies and, as such, is considered to be a very dangerous man and obviously has very close linkages with al-Qaeda," Mr Hayat said.
"He is certainly a very dangerous man and there is absolutely no place for such people in our society."
Mr Ghailani was captured in the town of Gujrat, where he and his associates had moved a month ago.
The authorities also say they seized weapons, computers and foreign currency in the raid.
The interior minister said the South Africans captured in the raid had not yet been identified.
South African press named them as Feroze Ganchi, a doctor of 30, and 20-year-old student Zubair Ismael, but also said concerns had been raised that they might have been using fake passports.
South Africa has applied to Pakistan for access to the men.
The BBC's Zaffar Abbas, in the Pakistani capital, Islamabad, says Pakistani security forces have killed or arrested several suspected Islamic militants in recent months.
But he adds that Mr Ghailani is the most significant al-Qaeda suspect to be apprehended since the arrest of the alleged mastermind of the 11 September 2001 attacks, Khaled Sheikh Mohammed, more than a year ago.