Four Revenue Canada employees have been suspended without pay following a criminal investigation by the RCMP, including two Revenue Canada officials arrested Tuesday, said federal Revenue Minister Jean-Pierre Blackburn Wednesday.

They will be suspended for the duration of an on-going criminal investigation by the RCMP.

The arrests centre around the companies of a Montreal businessman, Antonio Accurso. The federal revenue agency believes three of his companies, Simard-Beaudry Construction Inc., Construction Louisbourg Ltee. and Hyprescon Inc. had business dealings with two other shell companies meant to hide $4.5 million from the tax man.

The revenue agency contends the real companies would obtain receipts from the shell companies for fake contracts. The revenue agency suspects the hidden money may have been shared among the participants in the scam.

According to the minister, the discovery was made by using the regular internal processes of Revenue Canada designed to make sure work is being done according to the rules.