MasterCard Worldwide will introduce in the first quarter of 2007 a new service to help banks and other card issuers detect and stop PIN-based debit card fraud in real time. “From our perspective, a PIN transaction is probably the most secure transaction” a cardholder can make, said Jerry Sargent, MasterCard’s vice president of debit strategy and alliance development. The new service will add to that security while at the same time alleviating growing consumer concerns about online fraud, he said.