A solicitor for the Manchester property firm at the centre of an Assets Recovery Agency investigation has said his clients have done nothing wrong.
One of the premises raided was in Sale, Greater Manchester
Raids were carried out at home and business addresses connected to Dermot Craven and Brian Pepper on Thursday.
The searches are thought to be connected to inquiries into south Armagh man Thomas "Slab" Murphy.
Michael Kenyon, solicitor for the Craven property group, said his clients were astounded at the searches.
Sinn Fein said Murphy, who describes himself as a County Louth farmer, was being unfairly linked to criminal activity.
Newry and Armagh MP Conor Murphy said there was no evidence to suggest 250 properties being probed in Manchester belonged to Thomas "Slab" Murphy.
The DUP's Nigel Dodds said Sinn Fein's reaction showed its "duplicitous attitude towards criminality".
Documents were seized in the Manchester searches, which took place 10 days after the IRA put its weapons beyond use and on the day Sinn Fein President Gerry Adams met Prime Minister Tony Blair in Downing Street.
Meanwhile, separate searches took place in the Republic of Ireland connected to the probe into illegally held IRA funds.
Seven offices in County Louth were searched by officers from the Criminal Assets Bureau.
A quantity of documents were seized during the raids but no arrests were made.
Thomas Murphy lost a libel case against The Sunday Times in 1998, after the newspaper described him as a prominent IRA member.
The authorities on both sides of the border have been investigating him for years.