Internet giant Google Inc said it nearly doubled third-quarter profits on stronger advertising revenue and an increasing share of online searches.

Earnings climbed to $733.4 million, up from $381.2 million in the third quarter of 2005, the company said in a statement Thursday. Revenue was up 70 percent to $2.69 billion.

The Mountain View, California-based firm - which already holds the world's most used search engine - also increased its share of US searches to 44 percent in August, up from 37 percent a year earlier, research firm ComScore Networks Inc reported, cited by Bloomberg Financial news.

That marked another knock on chief Internet rival Yahoo Inc, which posted a 38-percent drop in profits Tuesday.

In another sign of the company's expansion into other Internet domains, Google last week announced a deal to buy online video site YouTube Inc for $1.65 billion.

"Their numbers just continue to astound Wall Street," Barry Ritholtz, chief investment of Ritholtz Capital Partners in New York told Bloomberg. "They're not sitting back and just getting fat and lazy."

Google's share price surged up more than six percent in after-hours trading on Wall Street Thursday.