New Hampshire and Vermont regulators will hold separate emergency meetings Sunday to reconsider Verizon’s $2.35 billion sale of its voice and Internet land lines in northern New England.

When the buyer, North Carolina-based FairPoint Communications, tried this week to sell $550 million in bonds to help finance the purchase, the best interest rate it could get was 13.5 percent, said Donald Kreis, general counsel for the New Hampshire Public Utilities Commission.

When the commission approved the sale in February, it believed FairPoint showed the deal was for the public good, and the anticipated interest rate was 8.5 percent, Kreis said.

The higher rate will cost FairPoint $17 million more per year in interest payments on the 10-year bonds, he said.

“It does affect the financing significantly in our case,” Kreis said.

FairPoint and Verizon hope to close the deal Monday.

Maine, Vermont and the Federal Communications Commission have approved the billion deal. Maine regulators accepted the financing changes, but Vermont regulators want to take another look, said Stephen Wark, a spokesman for the Vermont Public Service Department.

“The department will be watching these developments and closely analyzing the impact they could have on FairPoint’s ability to meet its obligations in Vermont,” he said.

“Our primary concern is to ensure this development does not adversely impact consumers.

“We’re crunching numbers right now,” he said.

“We will attend the hearing on Sunday. There has been no material adverse change in FairPoint’s financial condition from the completion of the financing arrangements,” said Verizon spokeswoman Jill Wurm.

FairPoint did not immediately return a telephone call for comment.

Regulators in all three states balked at the initial, $2.7 billion purchase price, questioning whether FairPoint had the resources to take over a regional communications network that would dwarf the rest of the company.

The companies retooled the deal in a way designed to reduce FairPoint’s debt.

New Hampshire regulators then approved the deal 2-1, attaching conditions including creation of a trust fund to cover unfunded liabilities establishment of a call center and a data center in the region.

Dissenting commissioner Graham Morrison said he wasn’t persuaded FairPoint had the fiscal capacity to meet its service commitments.

The Vermont Public Service Board’s meeting is set for 2 p.m. Sunday in Montpelier. The New Hampshire PUC will meet at 3 p.m. in Concord.