BEIJING - The team members spot-check about 100,000 products, spending about 100 million yuan (S$20 million) a year on average.
The whole process is videoed to retain the evidence.
The sample purchases are sent to copyright holders or authoritative quality inspection agencies. If identified as fake, the products are removed from the platform and the vendors face closure of their online shops. If the products are identified as genuine, they are stored as Alibaba assets.
Meet Alibaba's Anti-Counterfeiting Special Task Force, which was formed last year and has been actively working with local law enforcement agencies, according to team leader Qin Seng.
"The spot-checks are not random. They are guided by big data from our platforms," said Mr Qin. Using product ratings, consumer disputes and other information, the team builds a model to identify suspected counterfeit goods and the shops that sell them.
Alibaba's Storehouse of Counterfeit Evidence is a 300 sq m warehouse in the company's Xixi Park complex, in Hangzhou, the capital of Zhejiang province. Counterfeit goods can be stored there as legal evidence for more than three years.
The spot-checks illustrate the breadth of China's battle against counterfeits in the internet era.
Mr Chai Haitao, deputy director of the Office of the National Leading Group of the Fight against IPR Infringement and Counterfeiting, said the rapid development of China's internet economy means infringements and counterfeits are seen constantly.
"We need to strengthen cross-sector, cross-regional and cross-border co-operation to combat counterfeits. We also need to mobilise enterprises, industry organisations and the public," Mr Chai said.
Alibaba's team uses big data to identify counterfeits and the vendors, affiliated dealers and factories suspected of selling and producing fake items. They pass evidence to the public security authorities, and a number of other law-enforcement agencies, including those for commerce and industry, quality inspection, and food and drugs.
At the same time, the team members also investigate evidence in the field. Team members face many risks in their offline probes.
"Most counterfeiting dens are hidden and well-organised. For example, we encountered a village producing counterfeits. The villagers had installed cameras everywhere and when they saw outsiders entering, they became more vigilant and even threatened us," Mr Qin recalled.
Alibaba's co-operation with local authorities to locate sources of counterfeit goods has proved effective. The company has partnerships with public security bureaus in 13 provinces.
Last year, Alibaba submitted 1,184 leads to law-enforcement agencies, which helped public security bureaus arrest 880 suspects and assisted in the closure of 1,419 counterfeit manufacturing locations. In all, the operations seized merchandise worth more than 3 billion yuan.
In August, with evidence from Alibaba, police in Loudi, Hunan province, broke up a ring that produced and sold counterfeit weight-loss drugs.
With a sales network in more than 20 provinces, the ring's total trade exceeded 100 million yuan.
In the eyes of Mr Sun Jungong, Alibaba's vice-president, spot-checks and data-driven proactive monitoring protect the platform's good shopping environment, while co-operation with law-enforcement agencies is part of effective collaborative governance.
"We hope to take advantage of Alibaba's big data and strong data-mining capabilities. By expanding offline co-operation, we aim to tackle this issue at its source," Mr Sun said.
Professor Wang Xin at Peking University's Law School, said the rapid development of China's e-commerce platforms and the emergence of new online shopping models have provided a growing number of sales channels for fake goods.
He noted that China has made great efforts in recent years to stamp out infringements of intellectual property rights by strengthening laws and setting up specialist IPR courts.
However, he conceded that the penalties for counterfeit producers and vendors are not an effective deterrent because many producers of counterfeit goods only receive suspended sentences or fines.
Prof Wang suggested that repeat offenders should be banned from the credit market.
As Alibaba's Mr Qin said: "After we clean up online shops selling counterfeits, the counterfeiters usually change their identities and places of dispatch, using more covert means to continue selling online."
Alibaba's analysis has also established that some online consumers are happy to purchase counterfeits knowingly. Mr Sun said raising awareness among consumers is essential in the battle against fakes.
"Everyone can do their bit to stop counterfeit goods. If society reaches a consensus, as with drink-driving, we are more likely to tackle this problem effectively," he said.