Britain said it was urgently seeking information from the US Environmental Protection Agency (EPA) after it accused carmaker Fiat Chrysler Automobiles of illegally using hidden software to allow excess diesel emissions to go undetected, reports Reuters.

"We are urgently seeking further information from the US Environmental Protection Agency... and will also be seeking information from the manufacturer regarding vehicles in the UK market," a spokesman at the Department for Transport said on Friday.

Fiat Chrysler chief executive Sergio Marchionne angrily rejected the allegations on Thursday, saying there was no wrongdoing and the company never attempted to create software to cheat emissions rules by detecting when the vehicle was in test mode.

EPA accused the carmaker of fitting 104,000 of its cars with software which cheated pollution tests.

The agency said Fiat violated the Clean Air Act by installing and failign to disclose engine management software in Jeep Grand Cherokee and Dodge Ram vehicles with 3.0-litre engines.

"Failing to disclose software that affects emissions in a vehicle's engines is a serious violation of the law, which can result in harmful pollution in the air we breathe," said Cynthia Giles, assistant administrator of the EPA.

"We continue to investigate thenature and impact of these devices."

The allegation against Fiat came the day after Volkswagen pleaded guilty to criminal and civil penalties in the US over its use of defeat devices and agreed to pay $4.3 billion to settle the case.