The criminal – who ordered the murder of Real IRA terror chief Alan Ryan – was stopped during a routine traffic operation.
He was arrested along with a notorious criminal associate and questioned before being released without charge.
‘Mr Big' returned to the capital shortly after the killing of crime Godfather Eamon Kelly last week. The development has caused renewed fears of an-all out gangland bloodbath.
The gang boss fled in March and only returned to Dublin occasionally for short visits before Alan Ryan (below) was shot dead on his orders in September.
A source explained: "Mr Big is not back to avenge the death of Kelly. The most likely explanation is that he feels it is safer for him now that the Real IRA are feuding with each other.
"But he is sure not to let his guard down. The IRA mob would murder him on sight – there is a hit on his head."
'Mr Big' was stopped by officers in Dublin's south inner city during a routine traffic stop by officers from Kevin Street Garda Station.
The feared crimelord was in the company of a notorious hood from the East Wall area of Dublin's north inner city when officers pulled over the car the duo were travelling in at the Marrowbone Lane area.
'Mr Big' and his drug-dealing pal were questioned and searched but then allowed to continue on their journey after officers found no evidence of criminality.
Sources say that the gang boss, who is in his early 30s, "looked very tanned and was extremely relaxed" during his dealings with gardai.
Before his arrival back in Dublin last week, he is not thought to have been in the country since Ryan was murdered.
The return of the highly secretive crime boss has led to renewed fears of a brutal escalation of the feud between criminals and dissident Republicans which led to last week's killing of crime godfather Eamon Kelly (65) in Klllester, north Dublin.
Coincidentally, 'Mr Big' returned to the capital on the same week that a warrant was issued for the arrest of his close associate and mentor -- a veteran Tiger kidnap mastermind who is also suspected of involvement in organising Alan Ryan's murder.
The warrant was issued after the unpredictable veteran hood failed to show up at a court hearing where he was due to go on trial for serious offences.
The Tiger kidnap man, who is suspected of working with 'Mr Big' on around a dozen organised false imprisonment jobs, is believed to have fled Ireland shortly after the Alan Ryan murder.
Gardai have been working on the theory that 'Mr Big' and the Tiger kidnapping criminal planned the murder of Alan Ryan after their gang became entangled in a bitter feud, which kicked off after a nightclub assault this time last year.
'Mr Big' -- who comes from a respectable middle class background and is well educated -- has been striking fear into the underworld for years and he controls a vast patch of drug territory stretching from Clontarf all the way up to Drogheda, Co Louth.
However his stronghold is in the Coolock, Darndale and Donaghmede areas of the capital.
Key members of his gang are the notorious brothers who have been dubbed the 'Taliban' brothers after being linked to seven murders.
One of these brothers is in custody in a Northern Ireland jail while the other is on the run in a foreign country. Meanwhile, gardai from the Organised Crime Unit seized a major haul of cannabis and cash which was controlled by 'Mr Big' in a special operation in north Dublin last month.