The double-dip recession is deeper than originally feared as revised figures showed a sharper decline in the economy in the final quarter of last year.
Gross domestic product (GDP) shrank by 0.4% between October and December, compared with a previous estimate of 0.3%, while the economy contracted by an unchanged 0.3% in the first quarter of this year, the Office for National Statistics (ONS) said.
Dr Esmond Birnie, chief economist in Northern Ireland for business advisers PwC, said: "The big picture is that the UK economy has been broadly flat for the past 18 months."
He added: "If that's the case for the UK as a whole, it is likely that Northern Ireland is in recession territory, suggesting that 2012 will show no growth at best.
"That begs the question as to how the Executive can stimulate private-sector activity while under (huge) pressure to curtail public spending even further."
The downward revision will fuel criticism that Chancellor George Osborne's austerity measures are choking off the recovery.