Google parent company Alphabet is set to overtake Apple as the most valuable company in the world after announcing its financial results for the last three months of 2015.

The internet giant beat analyst expectations by reporting revenue of $21.3 billion for the final quarter of last year, up from $18.1 billion on the same period last year.

Quarterly profit for the period rose 5% to $4.92 billion on the back of strong online ad revenue.

The announcement saw the company's share price to rise by more than 9% in after-hours trading, taking Google's value above that of Apple.

Ruth Porat, chief financial officer of Google's parent company Alphabet said: "Our very strong revenue growth in Q4 reflects the vibrancy of our business, driven by mobile search as well as YouTube and programmatic advertising, all areas in which we've been investing for many years.

"We're excited about the opportunities we have across Google and Other Bets to use technology to improve the lives of billions of people."