SAN FRANCISCO - Google posted the first-ever decline in its quarterly earnings Thursday but still beat market expectations in the withering economic climate.

The web search giant said that it earned $382 million, or $1.21 per share, in the three months ending in December - a drop of 68 percent from the same period in 2007. But the profit was hit by a $1.5-billion charge for write downs on investments like AOL and Clearwire and the cost of issuing new stock options to employees whose existing warrants were below the company's share price.

Revenue increased 18 percent to $5.7 billion, or $4.2 billion once payments that Google makes to its ad partners were taken into account.

'Our business is quite healthy, especially given the economic climate,' Google chief executive and chairman Eric Schmidt said.

He warned that the company was heading into 'uncharted territory' as conditions could worsen in the shrinking US economy.

'We don't know how long this period will last,' Schmidt told analysts in a conference call. 'We obviously hope it will be short. We're certainly prepared to get through this, no problem.'

Shares of Google rose more than 2 percent in after-hours trading to $312.75, following the earnings announcement.