Beijing launched dual trade probes against goods imported from the European Union on Friday, less than a month after it agreed with Brussels to stabilise economic relations.
China's Ministry of Commerce said it had initiated an anti-dumping investigation into para-aramid filament yarns, a high-strength synthetic material used in cars, fibre optic cables, and bulletproof vests, imported from the EU.
The probe will assess whether low-priced imports are flooding China's market and damaging its domestic industry.
The same day, the ministry announced a similar probe into ethylidene norbornene imports from the EU and Japan.
The chemical is used to produce synthetic rubber materials common in construction and automotives, and to manufacture certain resins and plastics.
Both investigations will conclude in one year, though they can be extended for six months, the ministry said.
Anti-dumping investigations often lead to tariffs.
The probes come as China and the EU teeter on the brink of a trade war, despite crunch talks in Beijing last month producing a list of "understandings" to balance economic ties.
Brussels has called the bloc's ballooning trade deficit with China "unsustainable" and accuses Beijing of using subsidies and an undervalued currency to undercut European firms.
China rejects those accusations and has vowed to respond to any protectionist measures by the EU.
In October, China's commerce ministry launched an investigation into imports of the chemical p-nitrotoluene from the EU, complaining of "damage to production and operations" of domestic producers.
The chemical is used in the production of dyes, pharmaceuticals, and pesticides.
