Santiago, Jan 13 Chilean authorities are investigating a series of attacks and threatening incidents at churches in the Santiago metro area ahead of Pope Francis' three-day visit.

Members of the national police force's Police Special Operations Group (GOPE) were deployed to the municipality of Estacion Central after a bomb was found on Friday inside the Jesus Maestro church, the latest of five incidents, Efe news reported.

Although that home-made device did not detonate, the targeting of five churches in a short span has sparked concern among authorities three days before the pontiff's arrival.

Carabineros said a barrel of flammable liquid and pamphlets denouncing the Pope's visit, which is scheduled for January 15-18, also were found at the latest crime scene.

Three bombs exploded early on Friday in Catholic churches in the municipalities of Recoleta, Peñalolen and Estacion Central, while a fourth was found outside a church in the capital.

"Pope Francis, the next bombs will be in your cassock," a pamphlet found in one of the churches read.

Prosecutors suspect the so-called Lautaro Youth Movement, which allegedly carried out similar attacks on political offices in November and December, in the lead-up to the December 17 presidential runoff, also is behind these latest incidents.

In an interview with Oasis radio, President Michelle Bachelet described the attacks as "very strange," while the Archdiocese of Santiago said they "run counter to the spirit of peace inspired by the pope's visit."

President-elect Sebastian Piñera also condemned the attacks on Twitter as driven by "hatred and intolerance" and urged Chileans to receive Pope Francis with joy and in peace.

Separately, members of the "Andha Chile" movement of mortgage debtors protested at the Apostolic Nunciature, where the pontiff will stay while in Santiago.

The pope, who was born in neighbouring Argentina, also will make stops in the northern Chilean city of Iquique and the southern city of Temuco during his visit.