The founder of a British anti-litter campaign has become embroiled in a dispute with social media giant Facebook over the choice of the app's name.
Littergram invites smart-phone users to share pictures of rubbish on British streets and report the location to their local council.
The app was designed by Kent businessman Danny Lucas, 48, with the intention of helping to clean up British streets and educate children on the issue. His idea has been hindered, however, by Facebook officials, who say the app's name is too similar to the Facebook-owned photo sharing app Instagram.
US lawyers for the social media empire said the name was "not acceptable" and must be changed.
In a letter to Mr Lucas, the legal team said: "Our client appreciates the social objectives behind the Littergram project and the personal time, money and effort Mr Lucas has invested in it. However, having taken everything into consideration using Littergram as the name for the project is still not acceptable."
"It utilises and relies on social media usage to achieve its aims," it went on, "and our client cannot allow use of such a name in relation to services which are core to its world renowned activities in this area."
Mr Lucas has been given three to six months to "phase out" the app's title or face legal action.
The Littergram founder has described the argument as "absurd" and responded with a video-message to Facebook chief executive Mark Zuckerberg, asking him to retract the demands and work together with him to support the new app.
"Littergram has become a known name, it puts the Great back into Britain," said Mr Lucas.
"To change our brand identity because Facebook see us as a threat will destroy all of our ingenuity and hard work. We would be back to the drawing board, and have to start all over again.
"With no Government support or grant and from a standing start, I have put a huge amount of time, effort and money into the creation of Littergram to proudly arrive where we are today.
"I truly hope for the sake of the entire UK population, you will have the understanding and compassion to let Littergram continue."
Facebook announced earnings of $1.5bn (£1m) for the first quarter of 2016 this week – more than three times that of last year's earnings in the same period.
Instagram was bought over by the company for $1bn (£629m) in 2012 and is said to have more than 400 million monthly active users.
Facebook officials decided not release an official statement, but said the company had been engaging in conversation for several months to see if there was another way for Mr Lucas to market his app and not risk infringement of the Instagram trademark.
The company added that they had not yet filed a lawsuit against Littergram and hoped to come to an agreement over the names out of court.