March 26 (Reuters) - OpenAI's ChatGPT ads pilot in the United States has crossed the $100 million annualized revenue mark within six weeks of launch, a company spokesperson said on Thursday, pointing to robust early demand for the AI startup's nascent advertising business.

Sam Altman-led OpenAI had said in January that it would start showing ads in ChatGPT to some U.S. users, ramping up efforts to generate revenue from the AI chatbot to fund the high costs of developing the technology. The ads were to be tested with users on the company's free tier and the lower-priced Go plan.

The ads are separate from the answers generated by ChatGPT and do not influence its outputs. User conversations are not shared with marketers, the company said at the time.

While roughly 85% of users are currently eligible to see ads, fewer than 20% are shown ads daily, with considerable room to grow ad monetization within the existing user pool, the spokesperson said.

"We're seeing no impact on consumer trust metrics, low dismissal rates of ads, and ongoing improvements in the relevance of ads as we learn from feedback," OpenAI said.

The company plans to expand the test globally in additional countries in the coming weeks, including in Australia, New Zealand, and Canada. 

OpenAI has now expanded to over 600 advertisers, with nearly 80% of small- and medium-sized businesses signaling interest in ChatGPT ads, the spokesperson said. 

The ChatGPT maker is set to launch self-serve advertiser capabilities in April to broaden access and drive further growth. 

David Dugan, a former Meta ads executive, was named to lead OpenAI's global advertising solutions team earlier this week.

Analysts said that ads could unlock a significant revenue stream from millions of ChatGPT users, but the move could irk some customers and hurt trust in the product.