China is second only to the U.S. in terms of contributing to the volume of global spam and was long seen as a haven for spam servers due to a lack of willingness on the part of its government to prioritise the problem or accept its responsibility.
In the earliest days of spam reaching epidemic levels a large amount of traffic was directed via China, even if those profiting were based elsewhere, because the servers in Beijing and other Chinese cities were seen as being out of the reach of western governments.
However, at a ceremony attended by British ambassador Christopher Hum and U.S. federal trade commissioner Jon Leibowitz, China announced it will join international enforcement efforts against spam by adopting the London Action Plan on Spam Enforcement Collaboration.
China's original absence from the treaty was seen as an initial failing of the plan drafted last year.
UK ecommerce minister Alun Michael hailed the decision as a great result after months of negotiation between the UK and China.
"We have long been keen to engage with China on the issue of spam, in particular because China is probably the second biggest source of spam in the world," said Michael in a statement.
"As China reaches the 100 million Internet users mark, we welcome this opportunity to work with China to make the Internet safer for users."
Michael said the UK government intends to use its presidency of the EU to further push the anti-spam efforts.
China's representative in the London Action Plan, Union Network Beijing, will be responsible for dedicating a single point of contact for international discussion and the creation of an international working group on spam.
Silicon.com's Will Sturgeon reported from London.