Recent reports indicated that the Italian car brand had put the agency on three months' notice and that direct and interactive work in the UK and in several European markets was under review.
A joint statement put out by Fiat and Arc said: "Fiat Auto has not put either its UK or pan-European below-the-line account out to pitch. It is not talking to agencies."
Franck Ropert, Fiat Auto marketing director UK, said: "We would like to confirm that we are very happy with Arc's work over the last two years. We are not looking to review this relationship."
John Quarrey, CEO of Arc Marketing, added: "We have not been put on notice anywhere in Europe and are dismayed by continuing speculation."
Arc has worked with Fiat Auto for 15 years in Europe and seven in the UK.
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