In the first such ceremony on a papal flight, Pope Francis has performed a wedding for a steward and stewardess while flying between two Chilean cities.

Key points: Couple had civil union but religious ceremony was cancelled after church was damaged

Couple had civil union but religious ceremony was cancelled after church was damaged President of Latam airlines, Ignacio Cueto, witnessed the marriage

President of Latam airlines, Ignacio Cueto, witnessed the marriage Pope was travelling to Chilean city of Iquique, home to thousands of migrants

Paula Podest Ruiz, 39, and Carlos Ciuffardi Elorriga, 41, who had a civil union eight years ago, told the Pope a religious ceremony that was to follow was cancelled after their parish church in Santiago was heavily damaged in an earthquake in 2010.

They asked him to bless their marriage, but he had something else in mind.

"We told him that we are husband and wife. That we have two daughters and that we would have loved to receive his blessing. All of a sudden, he asked us if we were married for the Church too," Mr Ciuffardi told reporters afterwards on the plane, which was en route to the northern city of Iquique from Santiago.

The couple explained to the Pope how the 2010 earthquake had damaged the church they had hoped to marry in.

"He liked us and he asked: 'Do you want me to marry you?' He asked: 'Are you sure?,' Ms Podest said.

"'Yes of course,' we said."

The Pope performed the brief ceremony in the front of the plane.

Ignacio Cueto, president of Latam airlines, who was on board, was the witness.

An improvised marriage certificate was signed by the Pope, the couple, Mr Cueto and a bishop who was on the plane.

The marriage certificate of flight attendants Carlos Ciuffardi and Paola Podest. ( L'Osservatore Romano Vatican Media via AP )

"Being married by a pope on board a flight is something priceless," Ms Podest said.

"I asked him: 'Do you marry people?' He said: 'Yes, from time to time. I have married 40 couples.' But never has a pope married somebody on a flight," she said.

When the beaming couple emerged from the front section of the plane, some reporters in the rear section at first thought it was a practical joke.

Vatican spokesman Greg Burke came out a minute later to confirm it all.

"Everything is valid. Everything is official," he said.

"We had a short and small ceremony. He took our hands and he asked if there was love in our marriage and if we want to keep on being together all life long," Mr Ciuffardi said.

Ms Podest told reporters and the Pope that the couple had met on a flight when she was his boss, adding: "I am still his boss."

Iquique — the pope's destination — is a popular beach city in northern Chile that is also home to tens of thousands of migrants who have poured into the region's strongest and most stable economy in search of a better life.

The Argentine Pope, who has frequently demanded wealthy countries open their arms to migrants and refugees, called Iquique a "land of dreams" for so many newcomers and urged Chile to continue to be a place of hospitality, jobs and justice, especially for those migrants who are exploited.

AP/Reuters