BEIJING, April 15 -- The value of bonds issued in China in March hit 4 trillion yuan (616 billion U.S. dollars), nearly triple the figure for the same period last year, the central bank said Friday.

The value in March also more than doubled February's sum of 1.9 trillion yuan, according to the People's Bank of China (PBOC).

The total balance of the bond market reached 51.9 trillion yuan by the end of March.

The surge in bond issuance suggests it is becoming easier for Chinese firms to find affordable financing. Financing costs for companies through bond issuance has significantly reduced since 2014, according to the PBOC.

The central bank said Thursday that China will not limit investments by foreign central banks and similar institutions in the Chinese inter-bank foreign exchange and bond markets as long as they abide by Chinese laws and regulations and register their investments.