A lobbying firm working for a pro-coal industry group sent lawmakers a total of 13 fraudulent letters opposing the House climate bill — five more than initially believed, the House Select Committee on Energy Independence and Global Warming said Tuesday.

Tom Perriello (D-Va.) was one of a few lawmakers who received fraudulent letters opposing the House climate bill. (Photo: John Shinkle) The fake letters — sent to Reps. Kathy Dahlkemper (D-Pa.), Christopher Carney (D-Pa.) and Tom Perriello (D-Va.) — purported to be from the National Association for the Advancement of Colored People, senior citizens groups and Creciendo Juntos, a Hispanic advocacy organization.

In total, the firm sent 58 letters, and committee investigators suspect several more may be revealed to be fakes. The newly discovered letters included one, allegedly sent from a senior center in Charlottesville, Va., that the lobbying firm originally claimed was legitimate, the committee said.

Bonner and Associates, a firm that specializes in grassroots lobbying, was hired by the American Coalition for Clean Coal Electricity and by the Hawthorn Group, an Alexandria-based public affairs firm, as a subcontractor. Both companies have since denounced the company for the fake letters; Bonner and Associates has told POLITICO that the letters were sent by a temporary employee who has since been fired.

“As a part of both our internal examination and our full cooperation with the House Select Committee on Energy Independence and Global Warming, ACCCE is continuing to take all possible steps to determine the authenticity of all letters Bonner and Associates submitted under its limited scope of work with the Hawthorn Group on behalf of ACCCE,” said Lisa Miller, a spokewoman for the group. “ACCCE is sharing the information from our review with the Select Committee on an ongoing basis.”

Earlier this month, the Sierra Club formally asked the Department of Justice to open a criminal investigation into the letters.

New disclosures about the letters come as the climate debate heats up, with both sides using tactics that mirror those in the health care debate.

"We’ve seen fear-mongering with our nation’s senior citizens with health care, and now we’re seeing fraud-mongering with senior citizens on clean energy," said committee Chairman Ed Markey (D-Mass.), who’s focusing his investigation on checking the other 45 letters sent to lawmakers by Bonner.

Last week, efforts by a petroleum industry group to get employees and retirees to attend rallies attacking climate change legislation sparked a fierce debate within the energy community.

In a memo sent earlier this month, American Petroleum Institute President Jack Gerard described “energy citizen” rallies to be held in 20 states over the last weeks of the August recess.

Environmental groups slammed the events as manufactured grass-roots outrage.

Repower America, a group founded by former vice president Al Gore, and the Blue Green Alliance are hosting more than 50 events in 22 states, arguing that climate legislation would create jobs in clean energy and other new sectors.

In late June, the House narrowly passed climate legislation that would establish a cap-and-trade system to cut greenhouse gas emissions. The legislation faces a tough fight in the Senate, where it has come under fierce scrutiny from Midwestern and Southern Democrats.