NIG's Scottish-based risk management subsidiary All Risks Management (ARM) is expanding its operations into regions in England.
NIG hopes to improve the risks it takes on.
"NIG will be providing a better all-round service to brokers, and it will also mean brokers place better risks with us," said the spokesman.
Following a recruitment drive, ARM now has 20 staff.
"We're building up staff numbers in the regions to complement our offices in Glasgow and London," said a NIG spokesperson.
"The ARM people will talk to brokers in the regions and provide them, and their clients, with risk management advice."
ARM will concentrate on small to medium-sized businesses that pay premiums in the £10,000-25,000 range.