First Minister Arlene Foster has said sweeping new Covid-19 restrictions will last more than three weeks.
She said if she was a "betting person" she would think the measures will continue beyond Easter.
People must remain at home except for shopping for basic necessities, exercise, any medical need and travelling to and from essential work, Prime Minister Boris Johnson said.
Shops selling non-essential items were told to shut and gatherings in public of more than two people who do not live together are banned.
Mrs Foster told the BBC's Good Morning Ulster programme matters would need to be reviewed after three weeks.
Police will have powers to enforce the rules using fines and separating gatherings.
Today, the Stormont Assembly will debate the legislation which forces people to largely stay at home.
