NCA deputy director general Phil Gormley said the scale of offending discovered by the child abuse operation was "shocking".
His colleague, chief constable Simon Bailey, said the number of indecent images of children has risen from under 10,000 in the 1990s to a figure in the tens of millions today.
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Sunshine will follow the storms, moving slowly across the country from the west.
Donald Trump ordered new sanctions on Monday following a week of rising tension between the two countries.
Heavy rain could cause some localised flooding, forecasters have warned.