Online transactions now account for more than 15 per cent or €4.1 billion of sales by Irish retailers annually.

A survey published by the Ibec group Retail Ireland shows that 84 per cent of retailers currently have an online presence and that 64 per cent intend to upgrade theirs in the next 18 months.

The survey of more than 500 companies found that 62 per cent of retailers are now advertising on social media and about 50 per cent have plans to focus on smart phone applications and tablet technology.

Retail Ireland said this was with a view to tapping into the internet sales market, which the Digital Hub Development Agency expects to grow to €21 billion per year by 2017.

Respondents cited a number of barriers to online trading such as delivery costs (36 per cent) and initial set-up costs (28 per cent). Nearly one in four participants said poor broadband speeds, competition and the lack of post codes in Ireland were difficulties.

Less than two thirds of respondents said they were satisfied or very satisfied with their online retailing service at present, with one in five either very dissatisfied or dissatisfied.

Retail Ireland is holding its annual conference in Dublin today, which is to be addressed by EU consumer affairs commissioner Tonio Borg.