The Pope made his comments in a written message to people taking part in the VII World Congress on the Pastoral Care of Tourism being held April 23-27 in Cancun, Mexico.

With the theme "tourism that makes a difference," the congress brought together church leaders, government officials and representatives of international organizations, including the United Nations.

The importance of an ethical code or framework for the tourism industry as well as promoting socially responsible tourism were some of the topics being discussed at the congress. Talks included the fight against poverty and stopping the sexual exploitation of children.

In his letter, the Pope said, "Sexual tourism is one of the most abject of these deviations that devastate morally, psychologically and physically the life of so many persons and families, and sometimes whole communities."

"The trafficking of human beings for sexual exploitation or organ harvesting as well as the exploitation of minors, abandoned into the hands of individuals without scruples and undergoing abuse and torture, sadly happen often in the context of tourism."

Pope Benedict called on the international community, and especially pastoral workers and those working in the tourist industry, "to increase their vigilance and to foresee and oppose" the aberrations of sexual exploitation and the illegal harvesting of organs.

On the theme of tourism in general, the Pope underlined the importance of taking a break from work, saying "the enjoyment of free time and regular vacations are an opportunity as well as a right."

The church is dedicated to making sure that "this right will become a reality for all people, especially for less fortunate communities."

Vacation and free time are important for physical and spiritual renewal and can be occasions for encountering new cultures and getting closer to nature -- which in turn foster "listening and contemplation, tolerance and peace, dialogue and harmony in the midst of diversity," he said.

A more responsible and ethical kind of tourism must be promoted, he said, so that it "will respect the dignity of persons and of peoples, be open to all, be just, sustainable and ecological."