VATICAN CITY (Reuters) - Pope Benedict on Saturday condemned violence in God's name, but said that 10 years after the September 11 attacks, the world still had much to do to address the grievances that can give rise to acts of terrorism.

"Once again, it must be unequivocally stated that no circumstances can ever justify acts terrorism," he said in a letter to New York's archbishop, Timothy Dolan, who is also head of the U.S. Conference of Catholic Bishops.

Recalling what he called the "brutal assault" on the United States, the pope said: "The tragedy of that day is compounded by the perpetrators' claim to be acting in God's name."

"Every human life is precious in God's sight and no effort should be spared in the attempt to promote throughout the world a genuine respect for the inalienable rights and dignity of individuals and peoples everywhere," he said.

Benedict, who visited Ground Zero in New York during his trip to the United States in 2008, commended Americans "for their resilience in moving forward with hope and confidence," but said the root causes of violence still had to be addressed.

"It is my fervent prayer that a firm commitment to justice and a global culture of solidarity will help rid the world of the grievances that so often give rise to acts of violence and will create the conditions for greater peace and prosperity, offering a brighter and more secure future," he said.