TORONTO -- The head of the Canadian Federation of Independent Business says he is concerned that a deal struck between Wal-Mart (WMT.N) Canada and Visa (V.N) over merchant fees could lead to higher costs for smaller businesses.

Details of the agreement, which was announced Thursday and ended a months-long dispute between the two corporate behemoths, have not been provided by the companies.

But Dan Kelly, president and CEO of the CFIB, says he suspects Wal-Mart was able to negotiate a reduction in merchant fees -- a move that could impact smaller merchants.

"Typically whenever there is a special deal created for one large merchant, it happens at the expense of smaller merchants," he said, explaining that credit card companies and banks customarily look for other ways to make up lost fee revenue.

"We're going to have to watch this really closely to see if this special deal for Wal-Mart comes with higher prices for other smaller merchants."

CFIB, which represents over 109,000 business owners across the country, will continue to lobby Visa and other credit card companies for lower merchant fees for small- and medium-sized companies, Kelly added.

In July, Wal-Mart began refusing Visa credit cards at its three stores in Thunder Bay, Ont., citing excessive fees. In October, it extended that ban to Manitoba, where it has 16 stores.

As of Friday, Wal-Mart resumed accepting Visa at those stores.

Visa spokeswoman Carla Hindman said the company's agreement with Wal-Mart is specific to that retailer and doesn't affect other merchants.

"As previously announced, we have implemented rate changes aimed at lowering costs for businesses in Canada several times," Hindman said in an email.