After days of global protests among its users, Instagram has been forced to revert to less controversial advertising terms of service in a bid to maintain its dominance in the photo-sharing market.

In a blog post, co-founder Kevin Systrom has now apologised for the blunder. "Earlier this week, we introduced a set of updates to our privacy policy and terms of service to help our users better understand our service," he writes. "In the days since, it became clear that we failed to fulfill what I consider one of our most important responsibilities - to communicate our intentions clearly. I am sorry for that, and I am focused on making it right."

While the changes to the way Instagram communicates user data with its parent company, Facebook, will take effect next month, the terms relating to Instagram's advertising plans will remain unchanged for the time being. "The concerns we heard about from you the most focused on advertising, and what our changes might mean for you and your photos," writes Systrom. "There was confusion and real concern about what our possible advertising products could look like and how they would work. Because of the feedback we have heard from you, we are reverting this advertising section to the original version that has been in effect since we launched the service in October 2010."

These terms read: "Some of the Service is supported by advertising revenue and may display advertisements and promotions, and you hereby agree that Instagram may place such advertising and promotions on the Service or on, about, or in conjunction with your Content. The manner, mode and extent of such advertising and promotions are subject to change without specific notice to you [...] You acknowledge that we may not always identify paid services, sponsored content, or commercial communications as such."

Systrom has also reaffirmed the fact that Instagram will never sell its users' photographs. "You also had deep concerns about whether under our new terms, Instagram had any plans to sell your content. I want to be really clear: Instagram has no intention of selling your photos, and we never did. We don't own your photos - you do."

At the time of writing, however, numerous professional photographers, as well as organisations such as National Geographic, had yet to resume their activities on the photo-publishing platform.

And Instagram hasn't shelved its advertising plans, with Systrom indicating that his company will continue to develop these features. "Going forward, rather than obtain permission from you to introduce possible advertising products we have not yet developed, we are going to take the time to complete our plans, and then come back to our users and explain how we would like for our advertising business to work."