The family of Amy Fitzpatrick, who went missing in Spain eight years ago, believe there is an obvious fresh line of inquiry for Spanish police to pursue.
Speaking in the Dáil, AAA-PBP Deputy Mick Barry said it has been an unimaginable ordeal for Amy's father and aunt, who have never given up hope of finding her.
Amy was 15 when she disappeared in 2008 while living in Spain with her mother Audrey, stepfather David Mahon, and her brother Dean.
Mahon was subsequently convicted of stabbing Dean to death in Dublin in 2013 and is serving a seven year sentence.
Mr Barry said Amy's father Christopher Fitzpatrick and her aunt Christine believe there is a line of inquiry that police could pursue and said "the help of the Government here is needed to respectfully prompt the Spanish authorities to pursue this."
Deputy Barry said he was obviously constrained in what he could say on the matter.
Deputy Barry added that they had also written to the Minister for Justice seeking this to be done.
In response, Minister for Foreign Affairs Charlie Flanagan said the family had been provided with extensive consular assistance to the family and the garda's liaison officer remains in ongoing contact with Spanish police authorities on the case.
But he said his department could not play any direct role in the investigation process as this was a matter for the Spanish police who are still actively investigating the case.
Minister Flanagan said information on the case should be forwarded to gardaí who can liaise with Spanish authorities.
He agreed that representatives of his department would meet the family.