The UDA and other loyalist groups have been particularly active recently, carrying out many killings in the city. Yesterday's move appears to represent a determined security force drive to disrupt the organisations involved.
Paramilitary suspects in Northern Ireland can be held for up to seven days of questioning. Those arrested yesterday, many of them in early-morning raids, were taken to Royal Ulster Constabulary interrogation centres in Belfast and Armagh.
One of those held has achieved notoriety as one of the UDA's most active gunmen, and is now said to be the group's leader in west Belfast - the area centred on the Shankill district, the city's loyalist heartland. In the last two years he has escaped a number of republican assassination attempts.
Last week, another well-known figure in the Ulster Volunteer Force was arrested following the shooting of a Catholic woman in a rural area, but after some days in custody he was released without charge.
There were reports that guns and ammunition had been recovered during yesterday's operation.
Loyalist violence continued even as the arrests were taking place, with a UVF assassination attempt in the Woodvale area of west Belfast.
Gunmen opened fire and wounded a van driver making a regular delivery to a sweet-shop in a Protestant area. He was taken to hospital where his condition was said to be comfortable.
The gunmen lay in wait for him by taking over a house on Sunday night and holding a family captive.
In another loyalist attack in Londonderry city, a pipe-bomb exploded at a house, causing some damage but no injuries. The occupant lost both legs in a previous explosion in 1975.
The funerals took place yesterday of a Catholic man killed by loyalists in north Belfast on Thursday, and of a Protestant man who worked as a cleaner at an RUC station and was killed by the IRA on Friday.Reuse content