As the AP reported earlier, the U.S.-trained Egyptian biochemist, Magdy el-Nashar, 33, returned to Egypt about two weeks ago - which would be a week before the attacks - and showed up at the National Research Center in Cairo, which sponsors his work in Leeds. El-Nashar was arrested in Cairo on Friday.
El-Nashar was being interrogated by Egyptian authorities, the official said.
Metropolitan Police in London confirmed a man has been arrested in Cairo, but would not confirm his name or characterize him as a suspect. The British Embassy in Cairo said it had not comment beyond the Metropolitan Police statement.
One of the bombing suspects who died in the attacks, Jamaican-born Lindsey Germaine, had been in the U.S. within the past two years, ABC cited unidentified U.S. officials as saying. They are investigating people Germaine contacted in Ohio and New Jersey, the network said.
As Reuters reminds, British police say they are confident they can find an al-Qaeda link to the attacks in which four British-born Muslims, the youngest only 18, blew themselves up in separate attacks on three subway trains and a bus during the morning rush hour.