(Adds details of investigation)
SAO PAULO, Dec 13 (Reuters) - Gol Línhas Aéreas Inteligentes SA agreed to sign a leniency accord with federal prosecutors after an internal probe found the Brazilian airline wired money to firms under investigation in a sweeping corruption scandal.
In a Tuesday securities filing, Gol did not specify whether the payments were illegal although it said it agreed to pay 12 million reais ($3.6 million) in fines and penalties under terms of the agreement.
The settlement follows inquiries by tax authorities into payments for online advertising made to companies with ties to Eduardo Cunha, the former head of the lower house of Congress, who was arrested in October on bribery charges.
At the time, prosecutors said payments to those companies from holdings by the Constantino family, which founded Gol, did not appear to correspond with services of comparable value.
Henrique Constantino, one of four brothers who built the airline into Brazil's second biggest after LATAM Airlines Group SA left the board in August after he was targeted in the graft investigation shaking the country's establishment.
Prosecutors will present terms of the Gol accord to other government agencies concerned with the matter, according to the filing. ($1 = 3.34 reais) (Reporting by Guillermo Parra-Bernal and Gabriela Mello; Additional reporting by Brad Haynes; Editing by Jeffrey Benkoe)