Gardai believe a criminal gang is carrying out raids on targeted pubs in well-to-do areas of Dublin's southside.
Officers said a botched armed raid on a pub at the weekend was probably the work of a gang that had carried out at least one similar robbery in Dublin 4 in recent weeks.
The latest attack happened at Ashtons Gastro Pub in Clonskeagh at 2am on Saturday.
The methods used bore striking similarities to an armed robbery earlier this month at Bar 51 on Haddington Road in Ballsbridge.
In the Clonskeagh raid, two thugs wearing balaclavas entered the premises after a busy night and restrained two staff members with cable ties.
They appeared to be armed with a gun and a knife, and threatened staff and demanded money.
However, due to a sophisticated security system, no cash was available.
The frustrated raiders escaped with two bottles of vodka and two mobile phones owned by staff.
The raid on Bar 51, which took place at 1am on May 3, also involved two masked men armed with what appeared to be a gun and a knife.
No one was hurt, and the pair escaped with around €2,500.
"The similarities between these robberies have led investigators to conclude that the raids have been carried out by the same gang," a source told the Herald.
"Major investigations are in place, but there are serious concerns that this crew will target another pub in south Dublin before too long.
"They're clearly very hungry for cash."
In an unrelated incident, two south Dublin men were charged and remanded in custody over the weekend after a terrifying raid at the Fitzpatrick Castle Hotel, Killiney, late on Friday night.
Two masked men were reported to have entered the reception area at 10.50pm armed with a meat cleaver and a pick.
Gardai were told the raiders stole a cash register containing around €1,000 from reception but were then chased by staff before escaping in a getaway car driven by a third man in the direction of Shankill.
Gardai found the vehicle on fire at nearby River Close, Killiney, and three suspects from the Ballybrack and Loughlinstown areas, aged between 32 and 38, were arrested.
The cash register was recovered, along with a sum of money.
Two of the men arrested were remanded in custody after appearing before Dublin District Court on Saturday.
The third suspect was released without charge.