Gardaí estimate that Christy Kinahan, who was arrested in Spain last week after a major international operation, was responsible for importing more than €1bn worth of drugs into Ireland over the past eight years.

The 53-year-old is the source of most of the cocaine and cannabis that comes into the country and his arrest is likely to lead to a major drugs shortage on the streets in the short to medium term.

Gardaí involved in Operation Shovel, which included police forces in Ireland, Britain and Spain, believe Kinahan organised drugs shipments with a street value of over €1bn; some sources say the final figure could be as high as €1.5bn.

Gardaí have seized €70m worth of drugs sourced by Kinahan and his gang since 2002 and estimate that the seizures amounted to only five to 10% of the total drugs that reached Ireland undetected.

The Sunday Tribune has learned that Spanish police are planning another series of raids and that other Irish criminals could be arrested as early as today.

Criminals have already left their base in Puerto Banus and are assessing the implications of last week's events.

Kinahan, two of his sons and his right-hand man, John Cunningham, are in a Spanish prison waiting to learn the evidence that the Spanish police have built up against them. The four appeared before a judge yesterday and were remanded in custody.

The Sunday Tribune has learned the names of the six other Irishmen arrested during the operation in Spain. Gavin Abbot and Ross Browning have been released. Bernard Clancy, Tony Fitzpatrick, Kevin Lynch and Anthony Brown have all been remanded in custody. Garda sources in Ireland say they are not that well-known to the authorities here. They were among the 34 people arrested in Spain, Britain and Ireland last Tuesday morning.

Spain's interior minister has described Kinahan's gang as "one of the most dangerous ever tackled".

In addition to his drug activities, Kinahan, nicknamed the 'Dapper Don', has also been quizzed about the murders of two Irish citizens in Spain since 2008 and the attempted murder of one of his associates. However, it is understood that he will not be charged with any offences relating to these crimes.

Kinahan is the undisputed godfather of Irish drugs importation and has been based in Spain for over a decade. He is regarded by Europol as one of the biggest drug dealers in continental Europe and has built up a personal fortune of as much as €200m.

His Spanish assets were frozen by a court last week and the Criminal Assets Bureau is tracing his Irish assets, which include several legitimate businesses that have been used to launder drugs money.

Sources say it may be six months before the operation against him is completed. Fifty raids were carried out in Ireland last week and a large number of documents and financial files seized. One person was taken into custody but it is unlikely that any criminal charges will be filed here.

Gardaí have been liaising with their Spanish counterparts about Kinahan's gang for over two years through a detective sergeant who is on permanent secondment in Madrid.

With Kinahan's gang now effectively smashed, there is a vacuum in the drugs market. Gardaí believe Irish drug dealers will now abandon Spain in favour of Amsterdam.

Kinahan's arrest means the main drugs supply line into the country has ended, so new routes will have to be developed. This suggests that cannabis and cocaine will be in short supply for the foreseeable future.