The mouthpiece of China's Communist Party warned on Monday that Japan's economy could suffer for up to 20 years if Beijing chose to impose sanctions over an escalating territorial row.
Anti-Japanese protests have been held across China in recent days over a dispute over a group of small islands in the East China Sea claimed by both countries but controlled by Tokyo.
The row intensified last week when the Japanese government bought three of the islands, effectively nationalising them, and China responded by sending patrol ships into the waters around them.
Trade sanctions between Asia's two biggest economies could cast a pall over growth on the continent, which major Western countries are counting on to drive recovery from the global slowdown.
A commentary in the People's Daily newspaper said the Japanese economy has already experienced two lost decades from the 1990s and was suffering further weakness in the aftermath of the world financial crisis and 2011 earthquake.
"Japan's economy lacks immunity to Chinese economic measures," the commentary said -- although it added that given the interdependency of the two, sanctions would be a "double-edged sword" for China.
The commentary -- which only appeared in the paper's overseas edition -- said that Beijing in principle opposes economic sanctions to solve international disputes and would have to weigh carefully any decision to impose them.
But it added: "Amidst a struggle that touches on territorial sovereignty, if Japan continues its provocations China will inevitably take on the fight."
The commentary said possible targets could include Japan's manufacturing and financial industries, exports and investments in China as well as "strategic material imports," an apparent reference to rare earth metals used in many high-tech products.
"Would Japan rather lose another 10 years and even be ready to fall back 20 years?" it asked.
China and Japan have close trade and business ties, but their political relationship is often tense due to the territorial dispute and Chinese resentment over historical issues.
Numerous Japanese companies invest in China and two-way trade totalled $342.9 billion last year, making Japan China's fourth-largest trade partner, according to Chinese official data.
