San Francisco - Twitter on Monday added Instagram-style smartphone photo sharing features after the Facebook-owned service made it impossible for internet users to integrate its images into tweets."Starting today, you'll be able to edit and refine photos, right from Twitter," the globally popular one-to-many messaging service said in a blog post."Every day, millions of people come to Twitter to connect with the things they care about and find out what's happening around the world," it added."As one of the most compelling forms of self-expression, photos have long been an important part of these experiences."Twitter said its partner Aviary is powering "filters" and other effects for images using the latest Twitter applications for Apple iPhones or smartphones running on Google-backed Android software.BenefitA social media feud between Twitter and Instagram escalated over the weekend as the popular smartphone photo-sharing service made it impossible for internet users to view its images in "tweeted" messages.Instagram, which has some 100 million users, is seeking to route photo viewers to its own website, where it has the potential to make money from ads or other mechanisms, instead of letting Twitter get the benefits.Previously, Instagram pictures shared in messages tweeted from smartphones could be viewed unaltered at Twitter.Twitter indicated in a status update on Sunday that Instagram had "disabled photo integration with Twitter" and that "as a result, photos are no longer appearing in Tweets or user photo galleries"."While tweeting links to Instagram photos is still possible, you can no longer view the photos on Twitter, as was previously the case," Twitter said.Last week, Instagram had made it more difficult to view pictures in tweets, with the images cropped from the posts called Twitter Cards. By Sunday, the images were no longer viewable.The moves escalated the battle between the smartphone app Instagram, which was acquired by Facebook this year, and the popular message service Twitter.Instagram co-founder Kevin Systrom told a Paris conference last week that the move was part of a shift by the photo app to direct more users to the Instagram site.Instagram rose to stardom with the help of Twitter, but has distanced itself from the messaging service since being acquired by social network Facebook.Facebook completed its acquisition of Instagram in September. The original price was pegged at $1bn but the final value was less because of a decline in the social network's share price.Instagram in November was given a Facebook spin with the roll-out of online profiles that let people showcase themselves and photos they have taken with the smartphone application.People can share their profiles with whomever they wish, as well as "follow" other Instagram users, commenting on or expressing "likes" for pictures.A distinctive feature of Instagram is that it allows users sharing smartphone snaps to enhance them with image filters for artistic effects such as mimicking historic types of film.