NIG brokers now have access to Churchill's motor policies via a system called Project Damascus.
The scheme, which was piloted towards the end of last year, is currently only available to brokers who use CDL software. But it is understood the scheme is being rolled out to other brokers. Project Damascus's target is 50,000 policies by 2003.
NIG will make a profit by taking a commission on every policy sold. A NIG spokesman said: "We're hoping that this will strengthen our relationship with our brokers as they will be able to offer an extra competitive product to their customers."
Churchill chose NIG, a fellow company in the parent Winterthur Group, for Project Damascus because Churchill "lacks the support system to deal with a large number of brokers", according to NIG.
NIG denied it was setting itself up as a "virtual insurer".
"We don't imagine taking investment from venture capitalists," said the spokesman.