Pope Benedict XVI told the Vatican's diplomatic school that "faithfulness" is a key virtue for anybody working in the service of the Holy See.

"Certainly, this is something which ought to apply to every Catholic, and even more to every priest. Yet for those who work in the Holy See, it is of particular importance, since they spend much of their energy, their time and their daily ministry in the service of the Successor of Peter," he told the students and staff of the Pontifical Ecclesiastical Academy on June 11.

The Pontifical Ecclesiastical Academy is the training school for the Vatican's diplomatic service. In recent months the internal bureaucracy of the Holy See has been rocked by the ongoing disclosure of confidential papal documents to the media. Many of the leaks seemed aimed at the Vatican Secretary of State, Cardinal Tarcisio Bertone, who is directly in charge of the diplomatic service.

In his speech to the future diplomats at the Apostolic Palace, the Pope repeatedly stressed the need for faithfulness among those employed by the Vatican.

"God's faithfulness is the key to, and the source of, our own faithfulness," he said, telling the students that he "would like today to remind you of precisely this virtue, which well expresses the unique bond existing between the Pope and his direct collaborators, both in the Roman Curia and in the Papal Representations."

Pope Benedict specifically mentioned "with gratitude" the assistance he receives "every day" from his "many collaborators" in the Curia.

Faithfulness, he said, is "grounded in the priestly character," and its necessity can be amplified by the particular missions entrusted to those who serve the Successor of Peter.

The Holy See has formal diplomatic relations with the 177 states that have United Nations membership. It also maintains 110 permanent missions to foreign countries, along with delegations to international organizations such as the United Nations, the European Union and the Arab League.

As well as loyalty to God and the Church, the Pope told the future diplomats that they should "cultivate a relationship of profound esteem and benevolence" towards the "Churches and the communities to which you will be sent."

That faithfulness should also be "concretely manifested" each day by their "diligence and devotion to your work" and by their attentiveness to the "joy, sadness and even tragedy" of the to which they are sent. He urged them not to miss "all that God's grace has accomplished in every people and nation."

Updated at 3:12 p.m. MDT. Corrects number of governments with diplomatic relations with the Holy See to 177 and the number of countries to 110.