The Prime Minister announced during a visit to Shanghai in January that the Chinese project would serve as a model for up to 10 eco-towns that are scheduled to be built in Britain by 2020.
Such towns are a pet project for Mr Brown, and part of a strategy to show that Labour's commitment to the environment can match David Cameron's enthusiasm for all things green.
The involvement of a British company, Arup, in a Chinese landmark project has been heavily promoted by Mr Brown. "I want to mention the higher level of cooperation that is now existing on one of the greatest issues that faces the world, the environment," Mr Brown told an audience in Shanghai in January.
"We now enter a new era of cooperation that extends beyond the economy, a new era of environmental cooperation," he added.
The prime minister pledged to twin Dongtan with the Thames Gateway project, another Arup scheme to create "Britain's first eco-region".
He announced that Britain would give China £50 million from Britain's "Environmental Transformation Fund" to "support investment in energy efficiency and in renewables", and announced the creation of a "virtual sustainable cities academy" where researchers in the two countries could pool their ideas and information.
Notably, however, Mr Brown did not actually visit the site of Dongtan, despite Chongming Island lying only 45 minutes away by boat. A succession of other British politicians, including Tony Blair, John Prescott and Ken Livingstone, have all praised the "city" without ever setting foot on its site.
Meanwhile in Britain, plans to build such eco-towns have met strong opposition from the surrounding areas, with residents objecting that they are a flimsy excuse for building on greenfield sites and will choke the countryside with traffic. Campaigners have also been granted a judicial review of the government plans.
Ministers unveiled a shortlist of 15 possible sites in April which are set to be whittled down to "up to 10" next year.
Mr Brown promised in Shanghai that there would be "far better systems of transport, hydrogen-fuelled cars rather than cars fuelled by ordinary petrol, a whole range of systems for dealing with clean water and for the supply of energy. That is what eco-cities and eco-towns will offer in both Britain and China."
