It is getting harder for governments to buy U.S. Treasuries because the United States' shrinking current-account gap is reducing supply of dollars overseas, a Chinese central bank official said on Thursday.

The comments by Zhu Min, deputy governor of the People's Bank of China, referred to the overall situation globally, not specifically to China, the biggest foreign holder of U.S. government bonds.

Chinese officials generally are very careful about commenting on the dollar and Treasuries, given that so much of its $2.3 trillion reserves are tied to their value, and markets always watch any such comments closely for signs of any shift in how it manages its assets.