The battle to take control of a new internet domain aimed at environmental groups has escalated.
One of the consortiums preparing a bid to control .eco, as it is known, has published a 17-page analysis of a rival group's plan challenging its viability.
Dot Eco, a consortium backed by former US vice president Al Gore, describes a plan by its main competitor - Canadian green group Big Room - as "unworkable".
Big Room has said that publication of the analysis was "unfortunate".
"We're releasing this open examination because we're tired of Big Room's leaders mischaracterising our efforts and making exaggerations about their own plan, which after careful analysis proves to be unworkable," Fred Krueger, founder of Dot Eco, said in a statement.
Both groups are hoping to win the right to sell .eco "top-level domain names", which are similar to .com or .uk.
Dot Eco, which boasts supporters such as the Sierra Club and the Alliance for Climate Protection, aims to sell domain names to raise funds for green organisations.
It has already entered into contracts to give away 57% of its profits from sales, it has said.
Big Room, which is endorsed by WWF International and Green Cross, also plans to generate money from the sale of .eco domain names to fund "sustainability projects".
However, the consortium, also plan to use .eco as a labelling system to endorse companies with green credentials.
Only companies who meet agreed criteria - such as measuring and publishing their carbon footprint - would be granted a web address, a representative told BBC News.
Big Room also would like to see companies use .eco sites to publish all of their green information.
In the new 17-page analysis, Dot Eco claim that Big Room's operating costs will deprive green groups of "critical funding".
In addition, the group claims that Big Room's "cumbersome registration policies" will discourage take-up of the domain name and reduce possible funding for "urgent efforts to combat climate change".
Dot Eco also claims that Big Room "routinely mischaracterise" their plan in the press.
The Canadian Group has said it is aware of the analysis.
"It's unfortunate that they've taken this approach," Trevor Bowden told BBC News.
"We're not commenting on their response at this point."
The .eco domain has been made possible because Icann - the regulatory body that oversees net names - chose to relax the strict rules on top-level domain names.
The decision, made last year, means that companies could turn brands into web addresses, while individuals could use their names.