A third man has been arrested following anti-terror raids in Huddersfield and Sheffield.
The suspect was detained on Friday on suspicion of assisting an offender following raids on Thursday in which the first two men were detained under the Terrorism Act.
The North East Counter Terrorism Unit (CTU) said Thursday's operations in the Crosland Moor area of Huddersfield and in the Kelham Island area of Sheffield were not related to the investigation into the Manchester Arena bomb attack.
Two men from Huddersfield, aged 24 and 29, were detained on suspicion of offences under Section 5 of the Terrorism Act.
A CTU spokeswoman said they were held at separate locations in Huddersfield and Sheffield.
She said: "The two men arrested yesterday in Huddersfield and Sheffield remain in custody.
"A third man, age 23 and from Sheffield, has been arrested on suspicion of assisting an offender.
"Both property searches have now concluded and we would like to thank the local communities for their patience and understanding."
People living close to both locations reported being startled by large bangs and then seeing scores of police, many armed.
The CTU moved to reassure the public, saying the loud noises were part of police operations to gain entry to addresses.
People living around a block of flats between Dun Street and Cornish Street, close to Sheffield's Inner Ring Road, said the bang went off at about 5.30pm on Thursday.
One man who lived in the block said he saw a second-floor flat's door had been blown off.
Others said they saw armed plain-clothed officers in the triangular courtyard in the centre of the modern block.
The flats are fairly new, a short walk from the city centre, in an area which has seen a massive change in recent years, from a site of derelict 19th century industrial buildings to a series of residential flats redevelopments.
On Thursday night, cordons on the streets surrounding the property were lifted, although a number of police officers continued to guard the block, which is opposite the Shalesmoor tram stop, as a searches continued.
Similar scenes were reported in Huddersfield, where a large number of armed police were deployed in the Ellison Street area of the town.