'Fat' Freddie (31) arrived back on Tuesday after 14 months in Spain, leading to an increase in gangland tensions in the capital.
Freddie's money drive is being led by Daniel Kinahan (35) - the playboy son of Christy Kinahan (55), the jailed crime godfather who is the brains behind a multi-million-euro drugs and crime cartel.
A source explained: "The cartel are actively seeking to get money owed to them for drugs and they have enlisted Freddie and two of the capital's most feared criminals to do this for them."
The middle-aged criminals who are working with Freddie are from the Tallaght area.
They have stepped up a campaign of "intimidation and threats" against a number of serious players in the drugs trade based in Dublin and Limerick in a bid to force them to cough up the owed cash.
One of the hardmen is a notorious drugs trafficker who served a lengthy jail term for armed robbery in the 1990s.
Sources say that the relentless cash drive is causing massive underworld tensions and could potentially lead to a gangland murder.
A source explained: "The Kinahan organisation appears to be strapped for cash - they are pursuing debts of less than €5,000 but some dealers owe them far more than that. One fella owes them €100,000.
"Over a dozen major drug dealers are under very serious pressure because of this."
The Herald can disclose that one of the dealers feeling the heat is a massive drug trafficker from Cabra, north Dublin, who is now living in the Drimnagh area.
He was the chief target for the Garda National Drugs Unit's Operation Vulcan and is a main target of the Criminal Assets Bureau. Thugs linked to this crime boss are suspected of a pipe bomb attack on the family home of RTE star Brian Ormond in October, 2011.
The trafficker has been on the receiving end of "severe threats" and demands that he pay-up tens of thousands of euro owed to the Kinahan organisation.
Sources say that in another incident, a mid-level dealer who owes the cartel €16,000, was threatened by Thompson, who the Spanish authorities allege is a key member of the Kinahan association.
"The dealer was handed a mobile phone and Freddie Thompson was on the line.
"Freddie was screaming and roaring and warning what would happen to the fella if he did not pay up," said a source.
A source explained that the 'Kinahan cash drive' is also having dreadful consequences for innocent parents and families of drug dealers who got in way above their heads.
"We have a situation where decent, hard-working people are being forced to sell their cars or take out personal loans or even put their houses up for sale because of what is going on.
"They are being forced to cough up money for their children to save them from getting whacked. There are a lot of threats going around," a source explained.