The U.S. government says just one country, Afghanistan, has made significant improvements in easing restrictions on worship in the last year. A survey on religious freedom was released on the one year anniversary of the start of the war that led to the ouster of Afghanistan's repressive Taleban government.

This annual report by the State Department found that only Afghanistan saw significant improvement in religious freedom, something it says was brought about by the U.S.-led war on terrorism begun a year ago that led to the overthrow of the ruling Taleban.

But U.S. Ambassador for Religious Freedom John Hanford warns the world now needs to be on alert for groups like al-Qaida which seek to use religion to spread persecution across international borders.

"Religious-based terrorism by non-governmental actors, often with the support from rogue regimes, is emerging as a new cause of religious persecution," he said. "Terrorist organizations such as al-Qaida who define themselves and their goals in religious terms are growing in number."

Burma, China, Cuba, Laos, North Korea and Vietnam were all listed in this year's report as being among the worst violators of religious freedom over the past year. The governments of all six are accused of engaging in widespread religious repression, including harassing or arresting people practicing faiths other than those sanctioned by the state.

"Secondly, governments that build their legitimacy on a dominant religion often suppress minority religions. Here we find Saudi Arabia, Sudan, Iran," he said.

But U.S. ally Saudi Arabia did not make the list of the worst offenders, even though it is singled out as a country where religious freedom other than the practice of Islam, is not existent. But a U.S. official said the country's status is still under review and could be added to the list of countries of particular concern, the category reserved for the most egregious offenders, when it is submitted to Congress in the coming weeks.

By law, the State Department is required to report to Congress on the state of religious freedom around the world. Compiled from a variety of sources, the study's findings are used in shaping U.S. foreign policy.