The case has nothing to do with the ongoing investigation of the activities of Vilnius Vice-Mayor Romas Adomavičius, according to the authorities.
Vilkickas was detained on Thursday. After he was taken to custody, SIS officers searched his car, home, and offices at Vilnius Municipality building.
Another individual suspected of assisting Vilkickas in his criminal deeds was also detained.
If found guilty, Vilkickas faces up to seven years in prison.
Officers of the Lithuanian Special Investigation Service who detained Egidijus Vilkickas also inquired about documents in connection to planning of urban territories, the municipality's administrative director Valdas Klimantavičius said.
"I probably won't reveal a major secret if I say that the field of interest had to do with territorial and urban planning documents," Klimantavičius told journalists on Friday.
He also said the administration was awaiting answers from law-enforcement institutions to decide on whether Vilkickas should be suspended from office.
Klimantavičius said he would be in "shock," if the suspicions against Vilkickas proved correct.