Citing reports from Pakistan, The Guardian identified the men as Ibrahim Adam, 24, who fled the United Kingdom with his brother four years ago, and Mohammed Azmer Khan, 38, the brother of Abdul Jabbar, who was killed in a drone attack last year.
Adam and Khan, both Muslims from east London, had been under control orders issued by the home secretary to protect the public against a risk of terrorism.
Though reports of their deaths just emerged, Adam reportedly was killed six weeks ago while riding a motorcycle; Khan, two weeks later, the newspaper said.
The British Foreign Office could not confirm the deaths Friday but said, "We are aware of reports (of the deaths) and looking into them further."
Adam's father said, "We can confirm that we have heard that our son has been killed in a drone strike."
The family said he had been "executed" without having committed any crime.
In May 2007, Adam and his older brother, Lamine, were described as dangerous by Home Secretary John Reid.
The deaths come as reports from the region suggest the number of suspected militants being killed by U.S. drones may be rising sharply.