June 10 (Reuters) - OpenAI CEO Sam Altman told staff in a message earlier this week that he expected the AI startup to go public "within the next year," The Information reported on Wednesday.

The ChatGPT maker said on Monday it had confidentially filed for a U.S. initial public offering recently, joining rival Anthropic in a push toward a stock market listing as it looks to tap into insatiable investor demand for AI shares.

It did not, however, disclose the size or terms of the offering, and said a timeline has not yet been determined. "It may be a while because there are things we want to do that are likely easier as a private company," OpenAI said on Monday.

Altman said that "many things could cause it to be sooner or later in that range, but filing now gives us optionality if we want to go sooner," according to The Information report.

The OpenAI CEO also said in his message that if advances in the company's technology enabled its AI to create new AI on its own - known as recursive self-improvement - it could weaken the push for a quick IPO.

"The faster the potential RSI takeoff looks like it could be, the more it could be advantageous to delay an IPO," according to the report.

He also told staff that OpenAI is preparing to launch a tender offer "very soon" at the current share price of $687.69, The Information reported.

OpenAI said it had nothing to add beyond its Monday statement in response to a Reuters request for comment.

Reuters has earlier reported that the AI giant is targeting a valuation of up to $1 trillion in a stock market debut that could come as early as September.

(Reporting by Juby Babu in Mexico City; Editing by Anil D'Silva)