Boyband One Direction are facing legal action over their name from a US band who claim to have been using the same title for almost a year longer.
The Californian quintet have filed a lawsuit after they say their efforts to “negotiate a reasonable compromise” failed.
And they accused the X Factor group’s representatives of escalating the dispute by attempting to make them abandon their name.
It comes as the group - featuring Irish hearthrob Niall Horan - are taking the American charts by storm.
The US band, formed in 2009, said they liked the Irish/British act but added: “To protect our rights, we reluctantly have filed a lawsuit.”
In their legal action, the Californian group are aiming to stop Simon Cowell’s company Syco Entertainment and record company Sony from using the name and are asking for a share of the British act’s profits.
In an online message to their fans, they explained: “Despite our best efforts, we were unable to negotiate a reasonable compromise with the handlers for the band.”
The group - now on their second album -say they have the rights to the trademark “One Direction” in the US, and said their rivals had known about their claim to the name since the spring of 2011.
“They chose not to use a different name. They chose to press ahead, using the exact same name, One Direction, setting up the current difficulties and confusion in the United States,” the US act said in their blog.
And they added that lawyers for Horan, Harry Styles, Zayn Malik, Liam Payne and Louis Tomlinson had appeared before the US Patent and Trademark Office to challenge the longer established band’s right to the name.
The case echoes a legal dispute during last year’s X Factor. Series winners Little Mix were originally called Rhythmix, a name already adopted and registered by a music charity which then ran up legal fees defending its use of the trademark.
In their blog, the Californian group continued: “The British boy band is well funded and high profile. They have Mr Cowell’s enormous resources behind them. We on the other hand do not.
“In our view, we were here first. We have rights. We have talent, and we have heart. We are standing up for all of the above. Not having money does not take away your rights or make you ‘less than’.”
They wished the UK act well and added: “We wonder if they even know what their handlers are up to.”