Washington/Brussels, Nov 14 (Reuters) - The United States is headed for a showdown with much of the rest of the world over control of the Internet but few expect a consensus to emerge from a U.N. summit in Tunisia this week.

The very notion of "Internet governance" may seem an oxymoron to the 875 million users of the global computer network, which has proven stubbornly resistant to the efforts of those who wish to rid it of pornography, "spam" e-mail and other objectionable material.

But the United States, which gave birth to the Internet, maintains control of the system that matches easy-to-remember domain names like "reuters.com" with numerical addresses that computers can understand.

It worries countries like Brazil and Iran, which have pushed to transfer control to the United Nations or some other international body.

Even the European Union, where much of the business community backs the current system, has taken swipes at the United States.

"We just say this needs to be addressed in a more cooperative way ... under public-policy principles," said one EU official who asked not to be identified.

The issue is expected to dominate the World Summit on the Information Society, which begins Wednesday in Tunis, Tunisia.

Part diplomatic summit, part trade fair, the summit was launched two years ago with a focus on bringing the Internet and other advanced communications to less developed parts of the world.

That remains a hot topic for many of the 17,000 diplomats, human-rights activists and technologists expected to attend.

High-tech heavyweights like Intel Corp. and Alcatel will send top executives to talk up their development programs.

Researchers from the Massachusetts Institute of Technology will unveil a $100 laptop computer that can be powered by a hand crank in areas without a reliable supply of electricity.

But progress can't come without legal reform, business groups say. Internet access in the developing world will always remain expensive as long as governments allow their telecommunications monopolies to discourage competition, said Allen Miller, a senior vice president at the Information Technology Association of America.

"For most of these countries that are complaining about it, it's their own regulation and lack of liberalization that's preventing backbone providers from coming in," he said.

Over the past two years tension between the haves and have-nots has shifted from the question of who has access to the Internet to who controls its plumbing.

Diplomats were to meet on Sunday for a final round of negotiations before the summit. They might agree to set up a forum to discuss issues like cybercrime and spam, and countries might win more direct control over their own top-level domains, such as .nl for the Netherlands and .fr for France.

But the United States has said repeatedly it does not intend to cede control of the domain-name system to a bureaucratic body that could stifle innovation.

"No agreement is preferred to a bad agreement," U.S. Ambassador David Gross said at a recent public meeting.

Many experts say the Internet needs less government involvement, not more.

"When governments talk about imposing their public policies on the Internet, unfortunately they don't typically mean, 'Let's protect human rights, individual rights, let's guarantee the freedom of the Internet,'" said Milton Mueller, a professor at Syracuse University's School of Information Studies.

"They mean, 'Damn it, somebody using the Internet did something I don't like and let's find a way to stop it,'" he said.