By Jonathan Davies

Google is reported to be considering a takeover bid for Twitter, adding more than $1.5 billion (£1bn) to the social network's value.

A report by stock market analyst said that two companies contacted Twitter with "serious" interest. One of those companies is understood to be Google.

Twitter's shares jumped 4.8% after reports surfaced claiming it had hired Goldman Sachs as advisers to defend against any takeover bids.

Google has its own social network, but despite amassing more than 300 million users, Google+ has struggled to keep up with the likes of Facebook and Twitter.

This isn't the first time that rumours of a takeover bid have surfaced. In 2011, executives from both companies are reported to have held discussions of a possible deal.