Bloomberg reports that China’s top banking regulator said he’s “very worried” about risks emerging from bubbles in global financial markets and the nation’s property sector, sparking fresh concerns about further tightening in the world’s second-biggest economy.

Guo Shuqing, chairman of the China Banking and Insurance Regulatory Commission said that bubbles in U.S. and European markets could burst because their rallies are heading in the opposite direction of their underlying economies and will have to face corrections “sooner or later”.

China’s financial regulators are walking a fine line of trying to curb risks at home while limiting disruptions from abroad as the economy opens wider to foreign capital. The CBIRC vowed in January to stay “ahead of systemic risks,” after capping bank lending to the property market, slashing shadow banking activities and claiming victory in unwinding a wild expansion in peer-to-peer lending.

Regulators are watching capital inflows into China, where the economy is still growing and interest rates are higher, although the size and speed of such inflows remain controllable at the moment, Guo said.

Guo also said bubbles in China’s property market remain relatively big, with many people buying homes for investment or speculative purposes, which is “very dangerous.”