A team of detectives from the National Bureau of Criminal Investigations (NBCI), assisted by local gardai, swooped on premises at Coolock and Swords in north Dublin and Ratoath, Co Meath, early yesterday. The six were yesterday being held for questioning at five separate garda stations: Blanchardstown, Finglas, Whitehall, Coolock and Ballymun.

Gardai would not confirm whether the probes were part of a crackdown in the aftermath of a series of homicides in north Dublin in recent months. A garda spokesman said that the raids were part of an "ongoing operation into organised crime in the greater Dublin area".

A major probe is currently underway into the activities of a number of drugs gangs following the recent killings in the north Dublin divisional area. Last week, 22-year-old James Purdue was murdered near the Donaghmede home he shared with his partner and their toddler daughter.

On 2 June, 23 year-old Kevin Fitzsimons was shot dead near his Kilbarrack home by a gunman. He was not the intended target of the attack. Known criminal Patrick Harte was shot dead outside his Raheny home the previous week, just four days after drug-user Gerard Goulding was murdered in Donaghmede, on 24 April.

In a separate development, gardai were continuing to question a 23-year-old man yesterday following the seizure of 20,000 worth of cocaine in Finglas, Dublin.

The seizure was made at an apartment, and included 18,000 in cash. It is believed to be linked to the discovery of 30 kilos of heroin and cocaine in Malahide last February.

The drugs were reportedly brought in by a Coolock-based drugs gang working with another criminal gang in the UK. The 23-year-old man, who is from Liverpool, can be held for up to seven days.