U.S. officials announced plans Friday to relinquish federal government control over the administration of the Internet, a move likely to please international critics but alarm many business leaders and others who rely on smooth functioning of the Web.

Pressure to let go of the final vestiges of U.S. authority over the system of Web addresses and domain names that organize the Internet has been building for more than a decade and was supercharged by the backlash to revelations about National Security Agency surveillance last year.

The practical consequences of the decision were not immediately clear, but it could alleviate rising global complaints that the United States essentially controls the Web and takes advantage of its oversight role to help spy on the rest of the world.

U.S. officials set strict conditions and an indeterminate timeline for the transition from federal government authority, saying that a new oversight body must be created and win the trust of crucial stakeholders around the world, said Lawrence Strickling, a top Commerce Department official. The announcement essentially ruled out the possibility that the United Nations would take over the U.S. role, something many nations have advocated and U.S. officials have long opposed.

The looming change - if successfully executed - would end or at least dramatically alter the long-running contract between the U.S. Commerce Department and the Internet Corporation for Assigned Names and Numbers, a California-based non-profit group that goes by the acronym ICANN. That contract is due to expire next year, though in the past it has been repeatedly extended.

"I welcome the beginning of this transition process that you have outlined. The global community will be included in full," said Fadi Chehade, president of ICANN.

ICANN's most important function is to oversee the assigning of Internet domains - such as .com, .edu and .gov - and ensure that the various companies and universities involved in directing digital traffic do so safely. ICANN is midway through a massive and controversial expansion that is adding hundreds of new domains, such as .book, .gay and .army, to the Internet's infrastructure.

It long has faced complaints that the highly profitable domain name industry, which sells individual Web addresses for hefty markups, had established practical control over ICANN, to the detriment of other users. Rumors that the U.S. government would relinquish control were enough to alarm some business leaders on Friday.