Gardaí investigating the activities of a number of drugs gangs arrested six people at the weekend, following seizures of heroin, cocaine, a firearm, ammunition and stolen property.
One of those people being held is a 38-year-old, well-known Dublin armed robber and drug dealer.
He was recently released from prison, where he spent more than 10 years for kidnapping a young associate who was later murdered.
The latest three arrests took place on Saturday night after gardaí carried out two searches in the Weavers Court area of Clondalkin, Dublin 22.
They found heroin valued at €220,000 and arrested three people.
One of those arrested was a 21-year-old woman, while the other two were men aged 20 and 23.
All three were taken to Ronanstown and Lucan Garda stations, where they were still being questioned last night.
Gardaí believe the drugs are owned by a group of young criminals operating in west Dublin, mainly Clondalkin.
In an unrelated operation on Friday morning, gardaí arrested a 25-year-old man at an address in Ratoath, Co Meath, after they found a handgun, 50 rounds of ammunition and cocaine valued at €35,000 at the property.
The man is well known to gardaí in the area and was closely linked to the now deceased group of Blanchardstown-based criminals known as the Westies.
His house was raided as part of an ongoing operation into organised crime in the Blanchardstown and Finglas areas.
As well as the revolver, cocaine and ammunition, a quantity of stolen property was also found at the Ratoath house. Gardaí believe the items, which are valued at around €5,000 and include flat-screen televisions, were taken in robberies around the country.
The suspect was taken for questioning to Blanchardstown Garda station, where he was detained under Section 30 of the Offences Against the State Act.
On Friday night, a man and woman in their 30s were arrested after gardaí found heroin valued at €200,000 at a house in Clondalkin.
The drugs were found during the planned search of a house on Kilcronan Avenue at around 9.15pm.
The 38-year-old man and 32-year-old woman arrested were both taken to Clondalkin and Ballyfermot Garda stations. They were questioned under Section 2 of the Drug Trafficking Act.
The man has almost 30 convictions and is from Dublin's north inner city.
He had just been released from prison, where he served more than 10 years on concurrent sentences for two crimes.
In one case he was a member of a robbery gang that tied up a businessman, his wife and three young children, who were aged seven to 10 at the time.
He threatened them with guns during the course of a robbery on their home before robbing cash, goods and the family car.
The family were tied up for 17 hours.
The second crime took place in the mid-1990s, when he was part of a gang that kidnapped a young Dublin drug dealer in a dispute over missing drugs.
The young dealer was later tortured for a number of days before being shot dead.