New figures from the Central Statistics Office on the trade in goods reveal more evidence of a possible Brexit effect.
Under the Northern Ireland Protocol, trade in goods with Great Britain is subject to customs checks.
Northern Ireland remains legally within the customs territory of the UK, but remains effectively within the EU single market for the movement of goods.
Figures for the import of goods from Great Britain show a decline of 31% or €455m in March compared to March of last year.
This compared to slumps of 53% in February and 65% in January.
However, imports from Northern Ireland have gone up by 62%.
For the period January to March compared to the same three months in 2020, the value of imported goods from Great Britain fell by 48% or €2 billion.
But imports from Northern Ireland went up by 44% or €229m over the same three month period.
Today's CSO figures show that the value of exports to the UK in March went up by 13% or €139m compared to March last year, mainly due to an increase in the export of chemicals.
For the first three months of the year the overall value of exports to the UK is down 3% compared to the same time last year.
The export of food and live animal products from Ireland to Great Britain was down 20% in March compared to March last year.
The value of the same products exported to Great Britain was down 26% from €871m to €648m over the first three months of the year compared to the first quarter of 2020.
The import of food and live animals from Great Britain saw a greater decline. Imports in March were down 48% compared to March 2020 and imports of food across the first quarter were down 61% from €776m to €306m.
Total exports in goods, seasonally adjusted, rose by 1% in March to €13.2 billion, the CSO said.
Imports rose by 6% to €7.7 billion leading to a 7% or €392m reduction in the trade surplus to €5.5 billion.
Unadjusted figures for exports were down 17% in March compared to a year ago, reflecting an exceptionally high figure for exports in March of last year prior to the imposition of Covid restrictions.
Exports of chemicals were down 43% while exports of medical and pharmaceutical products, which account for 39% of goods exports, were down 7%.