An Indian restaurant faces a fine of up to £20,000 after two men were found working there illegally.
The Pakistanis were at the Indian Knights takeaway on the Cavehill Road, north Belfast.
Tuesday's operation was followed by raids at houses in the city on Thursday which detained two Chinese people and a Malawian. The Chinese woman and the Malawian were in the UK illegally and the Chinese man was a failed asylum seeker.
Mike Golden, assistant director of the UK Border Agency in Northern Ireland, said: "We will take action against those who are illegally in the UK and we will not tolerate illegal working which threatens to damage our communities and take jobs from legal workers.
"We will act on intelligence to target those businesses which ignore the rules and remove those with no right to be in the UK."
The restaurant could be fined up to £20,000 if it is found the owners did not carry out proper checks before employing the Pakistani illegal workers.
Mr Golden added: "Anyone who takes on a foreign national without permission to work in the UK is breaking the law, undermining law-abiding businesses and faces a big fine.
"There are strict rules about which foreign nationals can get a job in the UK and businesses have a clear responsibility to carry out the right checks."