The Irish Travel Agents Association (ITAA) has expressed "strong concern" over the effect Brexit will have on the Irish travel industry.
The inaugural Irish Travel Industry Summit has been held at Dublin's Clayton Hotel in Ballsbridge on Friday.
ITAA President Cormac Meehan says uncertainty and risk of Brexit will impact growth.
"Whatever happens to the macro-economy of Europe, post Brexit will affect us all.
"£According to data by Tourism Ireland, British holidaymakers travelling abroad in the future will spend 50% less while on holidays, 37% will reduce their holiday budget and 17% will postpone a trip outside of the UK".
He says this will mean a push by continental accommodation providers "to increase prices in an attempt to maintain margins" for Irish travel professionals.
"The traditional travel professional must get ready for a very different world."
Brexit will also see the renegotiation of the single sky treaty - which Mr Meehan says would see many low cost carriers "move their bases from the UK sooner rather than later."
"The uncertainty and risk are certain to impact our sector’s growth", he adds.
Mr Meehan and Pat Dawson, CEO of the ITAA, recently met with the Spanish and Portuguese national tourist boards.
They were told that these markets have anticipated drops in demand from the UK market.
Mr Meehan says: "It is our hope that holidaymakers from other European markets, such Germany, Denmark and the Netherlands, will help keep prices down for Irish consumers."
On the issue of Ireland's key connections with the UK, he says: "Increased border controls will stifle the movement of over 50 million people annually between our two islands and will result in many challenges for our Northern Ireland counterparts.
"A weak pound will mean that cost of sales will rise, margins will drop, and lower customer numbers will result in higher prices. Increased border controls will also impact staff mobility."
Central Statistics Office (CSO) figures from September showed a decline in the number of tourists from Britain.
The number of British visitors coming here fell 7.1% for the January to August period.
Tourism Ireland says the fall in the value of sterling has made holidays and short breaks here more expensive for British visitors.
The tourism body says it has placed a greater focus on a ‘culturally curious’ audience, who are less impacted by currency fluctuations.
But it says competitiveness and the value for money message are "more important than ever in Britain right now."
"Tourism Ireland’s extensive autumn campaign is in full swing, to promote late season holidays and boost travel into the early part of 2018".
The Irish Tourism Industry Confederation (ITIC) said the figures were a reminder that the Brexit impact on Irish tourism is "real and material".
The ITAA represents Ireland's travel Industry, bringing together 100 travel agent members and 70 affiliate partners.