Among the throng of bargain hunters at a flea market just off Dublin's Parnell Street, the day after the itinerary for the Queen's historic visit to Ireland was unveiled, republican sentiment was stirring.

Standing beside the tower of car tyres he was selling just outside the North Cumberland Street dole office, Christy Armstrong said that he was opposed to the three-day royal visit, which begins on 17 May. "Some people don't forget. It would not be appropriate. I remember what happened to the hunger strikers and other things the British did. But just because I don't want her to come here doesn't mean I want people to kill her. I would rather that any protests that are held are peaceful.

"As for the people living around this part of Dublin, I don't think most of them care. They are more concerned about the recession. I think they would rather choke a banker before they would choke her," he said.

The flea market is just a few hundred yards from the Garden of Remembrance, dedicated to the memory of "those who gave their lives in the cause of Irish freedom". This is one of the venues the Queen will – to widespread surprise – visit next month and where she will lay a wreath. She will also controversially visit Croke Park, home of the Gaelic Athletic Association and scene of the infamous massacre of 1920, when British troops opened fire on a crowd, killing 14 Irish civilians.

The itinerary is privately worrying members of the Garda Síochána, who fear republican dissidents will use the emotion attached to such sites to fuel a violent reception for the entourage.

A massive security operation costing more than €7m (£6.2m) is being put in place to protect the Queen and the Duke of Edinburgh. On Friday, six days after the murder in Northern Ireland of a Catholic police officer, Ronan Kerr, in Omagh, a second bomb attached to a vehicle was found hidden under a motorway bridge, possibly destined for a town centre, police believe. Chief Superintendent Alasdair Robinson said that the device was "sophisticated and substantial" and could have caused huge loss of life.

Clearly republican dissident activity is the major concern. But police also believe that demonstrations against the Queen's visit have the potential to turn violent, particularly in north inner-city Dublin.

The parents of Glasgow Celtic footballer Anthony Stokes were still in custody yesterday after gardaí raided their pub in Dublin's Fairview area. Their arrests were part of continuing operations directed against republican dissidents in the city.

John Stokes was last month ordered to remove a 40ft banner barring the Queen from his Players Lounge pub. A handful of bullets were found in an outside shed during the arrests, along with cocaine worth €500 (£440) and three stun guns. Stokes's wife, Joan, was also arrested, as was Paul Byrne, an uncle of the footballer.

Down on O'Connell Street outside the GPO, where the Easter Rising began in 1916 and where the Queen will pass on her way to Croke Park, demonstrators from the hardline group Republican Sinn Féin were collecting signatures in opposition to the royal visit as uniformed gardaí looked on.

Colum Moyes, an RSF activist from Dublin, said he was there to "demonstrate my opposition to a Queen who is head of armed forces that are still occupying six counties of my country in the north". Asked if there would be violence, he said: "I wouldn't know about that. There will definitely be protests, but I will probably be in jail because they [the garda] will lock as many of us up before she comes."

But as he spoke, a member of the public started remonstrating with one of his colleagues. Businessman Padraig Sweeney said the protest was "out of line".

"I run a B&B, and what we need in this city are more tourists from Britain. Welcoming the Queen means extending the welcome to more British people. That is what we want, not protests and living in the past," he said.

Back at the market, Dubliner Briege Daly described the forthcoming royal visit as "progress". As she rummaged through the stall, English rugby fans wearing the green, white and red Leicester colours mingled with residents, Irish Travellers, Nigerian and eastern European immigrants. Leicester were playing Leinster yesterday in the European Cup quarter-final at the Aviva Stadium.

She said: "It's time to move on and let bygones be bygones. What's in the past is in the past. I'm more worried about getting a bargain today."