U.S. securities regulators on Tuesday did not give Google Inc. (search) the green light it needs to price its initial public offering, extending the wait for its highly anticipated market debut.

The Securities and Exchange Commission (search) had not declared the Web search giant's registration statement effective as of the close of business on Tuesday, an SEC official said without elaborating.

The SEC opens for business at 9 a.m. EDT, and people familiar with the auction said the time frame could push the pricing of the IPO back until after the market closes on Wednesday.

Google had asked regulators to declare its registration statement effective at 4 p.m. on Tuesday, which would have given it the stamp of approval to end bidding for its shares and allow the company to set its IPO price.

The company could not immediately be reached for comment late on Tuesday.

Google is using a modified version of a Dutch auction (search) to sell its shares to the public, and it began collecting bids from potential investors last Friday. Google and selling stockholders are offering 25.7 million shares in the IPO, and the Mountain View, California-based company has estimated the shares will price at $108 to $135 each.

In a typical Dutch auction, the offering is launched at the highest price at which all of the shares offered can be sold to potential investors. But Google has left itself some wiggle room, saying it could price the IPO lower to get a wider distribution of its shares.

Google has said it will notify investors once its registration statement is declared effective, and it could then accept successful bids as soon as one hour after that.

Google's IPO Web site still said late on Tuesday that it expects to price the IPO the week of Aug. 16.

Deal watchers continue to speculate on the exact level of the pricing of Google's shares, given the recent downturn in Internet stocks and a flood of negative sentiment surrounding Google over the past two weeks.

In late July, Google issued financial results for the quarter ended in June showing that quarterly revenue growth had slowed to 7 percent, a sharp contrast to the double-digit gains in all previous quarters since 2002.

Later, the company disclosed that it may have issued more than 23 million shares and 5.6 million stock options illegally, triggering an investigation by California regulators.

Google said in additional filings on Monday that the SEC has started an informal inquiry into its offer to buy back the illegally issued shares.

Google has said it expects the owners of those shares and stock options to forgo the buyback offer and instead have them converted to registered shares at the IPO.

Some said Google's announcement that it would ask the SEC to declare its registration statement effective was a sign that it was attracting adequate demand for the deal.

Morgan Stanley and Credit Suisse First Boston are the lead managers on the deal.