Manchester property worth more than £1.5 million (€2.33 million) has been frozen following a court application by the North's Assets Recovery Agency.
Some of the property belongs to a brother of Thomas "Slab" Murphy, an alleged IRA leader. More court actions are expected.
The agency, the Northern equivalent of the Criminal Assets Bureau, alleges that the property portfolio is funded by the proceeds from money laundering, fuel smuggling and mortgage fraud and were purchased in the late 1990s early 2000s.
Nine of the properties frozen by the High Court in London belong to Mr Murphy's brother, Francis and his wife Judy, who have an address at Ballybinaby, Co Louth.
A 10th property, the ARA alleges, belongs to Julian Dowe from Sale, Manchester.
The Irish Times understands that the case was referred to the ARA by the Metropolitan Police in London following investigation by the force's Anti-Terrorist Squad.
It is further understood that Thomas "Slab" Murphy's farm on the Louth-Armagh border was searched as part of this investigation.
The court action follows a highly publicised search operation in Manchester in October 2005 which resulted in more than 350,000 pieces of evidence being taken for further examination.
ARA deputy director Alan McQuillan told The Irish Times: "Since that major search operation we have recovered large amounts of material and worked extremely closely with the Criminal Assets Bureau in relation to their investigation in Ballybinaby in Co Louth and we have a virtually seamless exchange of information."
He said "large numbers" of people had been interviewed under special powers and forensic examination of material recovered has been carried out.
"What we are seeing is the first stage of the next phase of this operation. That involves property which is associated with the Murphys. We have decided to move at this stage to prevent the dissipation of these properties."
The nine properties include two owned by Judy Murphy and another seven properties registered to the Murphys' property firm, Sailor Property (UK), which changed its name last August to FTM Properties.
Some of the Murphys' property is let to tenants and there is no suggestion they are involved in criminality.
According to the agency, Colin (also known as Colm) Farrelly from Dundalk is a director of FTM Properties but there is no allegation of illegal activity against him. The agency believes Mr Farrelly is a brother of Judy Murphy.
The agency alleges that Mr Dowe obtained his £450,000 home in Manchester through mortgage fraud.
The Irish Times believes he works for another Manchester property development company which was searched last year and that Mr Murphy's business interests are registered at that company's address.
The ARA investigation is proceeding in tandem with the Cab inquiry but there is no suggestion that there are further Manchester properties connected to the Murphys.
Mr McQuillan said: "The next stage will be the defendants' response. We are proceeding as quickly as possible. . . we are out for civil recovery of these properties."