The move by the EU, China's largest trading partner, signals growing international pressure on Beijing to crackdown on product piracy.
Power said it was too early to speculate on whether the 27-nation bloc would file a separate complaint over China's rules for intellectual property rights should the initial consultation phase fail to produce results.
"An efficient protection of intellectual property rights is an essential element in the protection of the interests of [EU] companies"
EU submission to WTO
The EU and Mexico filed their requests to join the talks at the WTO last week, trade officials said.
"An efficient protection of intellectual property rights is an essential element in the protection of the interests of [EU] companies," Brussels said in its submission.
It added that counterfeiting and piracy limits the value of investments in European research and development.
Mexico's request said it had a "substantial trade interest in this dispute" because of its increased trade with China.
The US filed two complaints on April 10 challenging Beijing's rules for copyright and trademark protection, and its alleged failure to remove import and distribution restrictions on copyrighted US goods including newspapers, magazines and video games.
Beijing, which says it has stepped up anti-piracy measures, criticised Washington's move and warned that the intellectual property case could damage bilateral trade relations.
Last week, a Chinese court ordered a Beijing company to pay $25,000 in damages to six US movie studios for selling pirated DVDs, the latest in a string of lawsuits over Chinese film piracy.
Under WTO rules, a 60-day consultation phase is initiated for any new case.
Any of the WTO's 150 members can seek China's permission to join the consultations.
While Beijing can reject the move, it would be powerless to prevent a country from initiating its own separate complaint at the Geneva-based trade referee.