Four men have appeared in court charged with a range of offences including assaults, threats to kill and extortion as part of an operation targeting an "epidemic" of drug debt intimidation offences.

Dublin District Court was told that Operation Fógra, across the city's northern region, has 30 ongoing investigations where individuals or households were targeted.

Detective Garda Domhnall O'Connell said some of the debts were small, but others were more than €100,000 or involved "houses being remortgaged".

He said there was a "drug debt explosion" as debts were more difficult to recoup due to the Covid-19 lockdown.

Four men were brought before the court.

They include Charlie Cunningham, 24, of Kelly’s Bay Heights, Skerries; Sean Jones, 19, who has an address at Kiltalown Way, Tallaght; his stepfather David Savage, 30, of no fixed address but from north Dublin; and Ryan Keeley, 20, of Coultry Place, Ballymun.

The Director of Public Prosecutions has directed trial on indictment in the Circuit Court, which has tougher sentencing powers.

Two of the cases were unrelated, but the backgrounds were similar and stemmed from a garda operation "targetting drug debt intimidation" the court was told.

Detective Garda O'Connell said the operation also investigated demands from relatives of people who supposedly owed money, and he objected to bail.

Pizza chef Charlie Cunningham is accused of threatening to kill or cause serious harm and demanding money with menaces.

The court heard he made no reply to the charges, and he met gardaí by arrangement.

Sean Jones made no reply when gardaí put four charges to him regarding two incidents.

He is accused of assault causing harm, aggravated burglary, demanding money with menaces, and producing an article during a dispute.

His stepfather David Savage was charged with taking part in an assault with Mr Jones on 1 January 2021.

He did not apply for bail and was remanded in custody for a week. He replied, "no comment" when charged, the court heard.

Garda Jane Keegan said Ryan Keeley has five charges, two for threats to kill and three demands for money with menaces in March and April last year.

He met gardaí by arrangement to be charged.

The judge granted bail to the three applicants.

However, she imposed strict terms. She warned them to have no contact with injured parties, provide gardaí with contact phone numbers, notify them of address changes, stay away from areas where the offences happened, and sign on three days a week at their local garda stations.

Judge Kelly said they were very serious charges. She ordered them to appear again on 24 June to be served with books of evidence and returned for trial.

The judge granted legal aid.

They have not yet indicated how they will plead.