A 43-year-old criminal who has been a long-term target of gardai is in custody after officers seized €300,000 worth of drugs belonging to the Kinahan cartel.
Detectives also arrested a 22-year-old man during five raids in Dublin's south inner city early yesterday.
During the raids - part of Operation Thistle - investigators seized €300,000 worth of cocaine, heroin and cannabis resin.
Members of the Drugs and Organised Crime Bureau, the Special Detective Unit and the Criminal Assets Bureau were involved in the raids, which were led by officers from Kevin Street Garda Station.
The two suspects were still being questioned at Kevin Street and Kilmainham Garda Stations last night.
The main target of the operation was the older man, who is based in the Mount Browne area of the capital.
Sources said he is a key associate of the Christy Kinahan cartel and is suspected of many years' involvement in major drug-trafficking activities.
He was previously arrested by gardai investigating the gangland murder of Johnny 'Champagne' Carroll in February 2009.
Carroll, from Charlemont Street, was shot dead in Grumpy Jack's pub in the Liberties.
CCTV footage of the killing showed that the gunman seemed to know what Carroll looked like and where he would be sitting. A man wearing a helmet walked into the pub and fired several shots at Carroll with a semi-automatic weapon.
The 43-year-old criminal arrested yesterday was never considered a suspect in the Carroll case, but was arrested for withholding information about it.
He has continued to operate a "thriving" drugs business in the south inner city. Until yesterday, he had managed to elude gardai.
Sources said that officers were "very satisfied" with yesterday's search operation, which was the biggest drugs seizure in several weeks.
"This is a great result because it has taken a large amount of drugs out of circulation and also led to the arrest of a significant player in the cartel," a senior source told the Herald.
"He is a mid-ranking but trusted member of that criminal organisation and has been on the garda radar for years.
"This is all about disrupting the activities of the cartel. These operations are going to continue throughout the summer months."
During yesterday's operation, the homes of notorious heroin trafficker Greg Lynch and his father Gerard 'Bra' Brady were among a large number of properties raided by gardai investigating the activities of the cartel.
In connected garda raids in March, gardai seized more than €40,000 from the Liberties home of a young criminal who has been acting as a driver and business partner of Lynch.