A 31-year-old man arrested on suspicion of terrorism offences is a Rainhill office worker, police have said.
The man, who has not been named, remained in custody on Thursday morning and is being questioned by senior anti-terror officers.
Police have seven days to charge or release the man.
He was held following a dramatic swoop by police at an office in View Road, Rainhill, on Wednesday morning.
Police simultaneously raided four addresses in Kensington, Liverpool, where the suspect is believed to reside.
A force spokesman said police had now finished searching the Rainhill address, where the suspect works.
It is understood the business itself is not connected to the investigation.
The raids followed tip-offs from other police forces.
“We were following up information provided to us by other police forces,” said a spokesman for Greater Manchester Police, which is leading the investigation.
“No plot was uncovered. I think it is fair to say that at this stage we’re no focusing on any particular background, religious or otherwise.”
Police searches of properties in Liverpool, meanwhile, could take up to several days to complete.
Det Chief Supt Tony Mole, from the North West Counter Terrorism Unit, said: “The NWCTU are currently conducting a joint investigation with Merseyside Police following the receipt of information from law enforcement agencies.
“It is our intention to carry out a thorough, professional investigation to determine the circumstances and details of the activity reported.
“We are taking all measures necessary to ensure public safety, which is our primary concern.
“Members of the public will see a lot of police activity at a number of addresses in the coming hours and possibly days.
“However, it is absolutely vital to stress – and I hope at the same time reassure the public – that there is no current threat or evidence of an imminent attack.
“We will of course keep the public informed as things progress and would once again encourage them not to be unduly worried.”
Anyone with concerns about suspicious activity should contact local officers or the confidential Anti-Terrorist Hotline on 0800 789321.