Micro-blogging giant Twitter has updated its photo-sharing features in a move designed to directly compete with Facebook.

The update allows users to “tag” friends in the photos they post to the site, as well as share more than one image at a time, something not possible until now.

Facebook has had both features for some time, and this update follows a design overhaul earlier this year which saw photos given higher priority when composing a new tweet.

The update comes as Instagram, the photo-sharing social network, announced it had passed 200 million users. This figure is closing in on Twitter's number, which stands at more than 240 million.

Industry experts also pointed to statistics which show Instagram users have surpassed Twitter in the US for the first time. With the new features, when users select a photo to tweet, a new button labelled “Who’s in this photo” appears, enabling users to tag friends.

From the existing photo selection screen, it is now possible to choose up to 10 images to post in a single tweet, intsead of just one. “Photos just got more social,” said Twitter in a blog post announcing the update. “We’re rolling out two new mobile features that make photos on Twitter more social. Tagging people in a picture makes conversations around photos fun and easy.”

Currently more than 500 million tweets are sent every day.