The value of Instagram has increased once again, according to Citigroup estimations.

On December 20, the firm raised its value of the photo-sharing app from $19 billion to $35 billion, Digital Spy reports citing TechCrunch.

The figure is a sharp increase from the $1 billion Facebook paid for it back in 2012.

The app's latest valuation has been helped by recent news that it has overtaken Twitter's number of users with 300 million members.

Twitter's user base currently stands at 284 million, putting Instagram ahead by a considerable margin.

Earlier this week, the app was given five new filters. The company has also deleted millions of spam accounts.