Up to 70% of online sales are going to companies based outside Ireland, according to Retail Excellence Ireland, which says Irish retailers have found business quite challenging so far this festive season.
Overall Irish retailers are reporting sales are up to 2% higher than last year, but many are still hoping for a surge in business this weekend.
REI's commercial director JP Kennedy says online sales are still having an affect on businesses, but they are catching up.
The group say that they are pinning their hopes on a busy shopping weekend ahead as they look for a surge in business before Christmas.
Many shops have found business quite challenging in recent weeks despite strong Black Friday sales.
The number of people doing their Christmas shopping in stores remains unchanged compared to last year.