Jan 12 (Reuters) - The U.S. Environmental Protection Agency on Thursday will accuse Fiat Chrysler Automobiles NV of using software that allowed excess diesel emissions in just over 100,000 U.S. trucks and SUVs sold since 2014, two sources briefed on the matter said.

The EPA told the automaker it believes its undeclared emissions control software allowed vehicles to generate excess pollution in violation of the law. Fiat Chrysler declined to comment.

Its U.S.-listed shares were down 9 percent.

The EPA will announce the findings at an 11 a.m. conference call. It comes amid rising scrutiny by EPA of automaker emissions after Volkswagen AG admitted to cheating diesel emissions tests in 580,000 U.S. vehicles.

The EPA has for months declined to certify Fiat Chrysler's 2017 diesel vehicles for sale in the United States.

(Reporting by David Shepardson; Editing by Nick Zieminski)

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