The couple were said to live in England, reports ANSA news agency.

The investigation began after the Colosseum Park Authority was alerted to the incident by a video, allegedly filmed by the pair and posted on social media, the news agency reported.

Investigators earlier said the young tourist risks at least a 15,000 euro fine and up to five years in jail for the act of vandalism.

"I am grateful to the Carabinieri for having promptly identified the alleged perpetrator of the uncivilised and absurd act committed at the Colosseum," Italian Culture Minister Gennaro Sangiuliano was quoted as saying by ANSA.