A senior Vatican bishop has warned Roman Catholics that they should be aware of new sins such as causing environmental blight.

The guidance came at the weekend when Archbishop Gianfranco Girotti, who is number two in the Vatican Apostolic Penitentiary which deals with matter of conscience, spoke of modern evils.

Asked what he believed were today's new sins, he told the Vatican newspaper L'Osservatore Romano that the greatest danger zone for the modern soul was the largely uncharted world of bioethics.

He said that within bioethics there are areas where we absolutely must denounce some violations of the fundamental rights of human nature through experiments and genetic manipulation whose outcome is difficult to predict and control.

The Vatican opposes stem cell research that involves destruction of embryos and has warned against the prospect of human cloning.

Archbishop Girotti, in an interview headlined New Forms of Social Sin, also listed ecological offences as modern evils.

He went on to mention excessive wealth and drug dealing as forms of social sin that contravene God's law.

In recent months, Pope Benedict has made several strong appeals for the protection of the environment, saying issues such as climate change had become gravely important for the entire human race.

Under Pope Benedict and his predecessor John Paul, the Vatican has become progressively green.

It has installed photovoltaic cells on buildings to produce electricity and hosted a scientific conference to discuss the ramifications of global warming and climate change, widely blamed on human use of fossil fuels.

Archbishop Girotti also listed drug trafficking and social and economic injustices as modern sins.

But the archbishop also lamented that fewer and fewer Catholics go to confession at all.

He pointed to a study by Milan's Catholic University that showed that up to 60% of Catholic faithful in Italy stopped going to confession.

But the same study by the Catholic University showed that 30% of Italian Catholics believed that there was no need for a priest to be God's intermediary and 20% felt uncomfortable talking about their sins to another person.