Pope Benedict XVI issued a call for world peace in a letter to Iranian President Mahmoud Ahmadinejad released on Thursday, saying religious people could play a key role in spreading harmony.

"When the promotion of the dignity of the human person is the primary inspiration of political and social activity... solid and enduring foundations are created for building peace and harmony between peoples," he wrote.

"Peace is, above all, a gift from God, which is sought in prayer, but it is also the result of the efforts of people of good will. In this perspective, believers of every religion have a special responsibility," he added.

The letter, which was made public by the Vatican press office, was a reply to a missive from Ahmadinejad last month in which the Iranian leader called for stronger bilateral relations with the Vatican to fight secularisation.

Benedict's letter also called for talks on the status of the Catholic Church in Iran and referred to pressures on Christian minorities in the Middle East.

"I am... convinced that the launch of a bilateral commission would be especially helpful in addressing questions of common concern, including that of the juridical status of the Catholic Church in the country," he wrote.

Referring to Christian communities, he said: "In some countries these communities face difficult circumstances, discrimination and even violence and they lack the freedom to live and publicly profess their faith."

Benedict's reply was presented to Ahmadinejad in Tehran on Tuesday by Jean-Louis Tauran, a cardinal and head of the Pontifical Council for Inter-religious Dialogue, but its contents were only made public on Thursday.