Only 39 of those arrested were registered sex offenders known to the authorities.
45 police forces were involved in the early morning raids in England, Wales, Scotland and Northern Ireland searching more than 800 properties.
When the police start searching the computers, we might see lots more arrests and maybe many more around the world.
One arrested man had access to 17 grandchildren – two of them had already made allegations against him.
Two men, one of whom is a doctor, had between them more than a million indecent images of children on their phones and computers.
Care workers, Scout leaders, teachers, Doctors and former police officers were also among the hundreds arrested.
A total of 431 children now under official protection had been in the “care, custody or control” of suspects, 127 of those children were considered to be at immediate risk of harm, the agency revealed.
The NCA’s deputy director general, Phil Gormley, said: “This is the first time the UK has had the capability to coordinate a single targeted operation of this nature.
“Over the past six months we have seen unprecedented levels of cooperation to deliver this result.
While Mr Gormley refused to discuss the tactics used to snare the suspected paedophiles it is believed many of those arrested had been operating on the so-called Dark Web, a part of the internet, which has in the past been extremely difficult for the authorities to monitor and police.
But Mr Gormley said sex offenders should realize that they cannot avoid detection while using the internet, even the dark web.