SAN FRANCISCO (REUTERS) - Facebook Inc's fourth-quarter revenue jumped 63 per cent, beating Wall Street targets, as the Internet company's mobile ad sales continued to accelerate.

Shares of Facebook were up 7 per cent at US$57.36 (S$73.21) in after-hours trading on Wednesday.

The world's largest social networking company said that revenue from mobile ads represented 53 per cent of its total advertising revenue in the last three months of the year, or US$1.24 billion, versus the 49 per cent proportion that mobile ads represented in the third quarter.

Facebook said it now has 1.23 billion monthly users, with 945 million accessing the service on a smartphone or tablet.

Overall revenue in the fourth quarter rose to US$2.585 billion, compared with US$1.585 billion in the year-ago period and above the US$2.33 billion expected by analysts polled by Thomson Reuters I/B/E/S.

Facebook reported net income of US$523 million, or 20 cents a share, versus US$64 million or 3 cents a share in the year-ago period. Excluding certain items, Facebook said it earned 31 cents a share.