Japan's holdings of U.S. Treasuries dipped below $1.2 trillion for the first time since 2013 even as purchases of the government debt accelerated among foreigners as a whole.

Japan, the second-largest foreign holder, saw its holdings fall by $17.8 billion in June, the biggest drop in two years, to $1.197 trillion, according to Treasury Department data released Monday in Washington. China's holdings of Treasuries rose by about $900 million to $1.27 trillion.

Net foreign purchases of Treasuries were $69.8 billion in June, the most since February last year, after $53.4 billion in buying in May, the report showed. Foreigners sold U.S. equities, pared purchases of corporate debt and increased buying of U.S. agency bonds.

The Treasury's report, which also contains data on international capital flows, showed net foreign purchases of long-term securities of $103.1 billion in June.

It showed a total cross-border outflow, including short-term securities such as Treasury bills and stock swaps, of $110.3 billion.