A trade group representing U.S. community banks called today for a moratorium on mergers involving financial firms with more than $100 billion in assets.

The Independent Community Bankers of America (ICBA) made its pitch to regulators at the first in a series of public hearings the Federal Reserve is holding to review Capital One Financial Corp.’s proposed takeover of ING Groep NV’s U.S. online banking portfolio.

Chris Cole, senior vice president of ICBA, said there should be a moratorium on big bank mergers until rules from last year’s Dodd-Frank Wall Street Reform and Consumer Protection Act are defined and in force.

“It has been 14 months since the Dodd-Frank Act was passed and we still don’t have a regulatory apparatus in place to deal with those banks over $50 billion in assets … and haven’t figured out an accurate way to measure their systematic risk,” he said.

Dodd-Frank requires U.S. regulators to take systematic risk into account when evaluating a merger, in addition to public benefit, concentration of resources, unfair competition and other factors.

Capital One defended the merger at the hearing, telling the Fed and community groups that big does not necessarily mean risky.