Pope Francis appointed a new Vatican spokesman on Thursday, tapping British-born Matteo Bruni for one of the most demanding PR jobs in the world.

Bruni, who has worked in the Holy See Press Office since 2009 and coordinated the press on the pontiff's international trips since 2013, takes over from interim spokesman Alessandro Gisotti.

He will have his work cut out for him with Francis, whose schedule is packed full of audiences with world leaders and visits abroad.

His first big story to manage is likely to be the forensic investigation Saturday into two ossuaries discovered under a Vatican trapdoor, tipped to possibly contain the bones of an Italian teenager who went missing 36 years ago.

"The Press Office has a new director, Matteo Bruni, who knows perfectly how we work and has been appreciated over the years for his people skills and professionalism," said Paolo Ruffini, the head of Vatican communications.

Bruni, 42, said the appointment was "an honour" and he was "grateful for the trust of the Holy Father".

"The Press Office is not a large structure, but it is a complex one," he added.