The People's Bank of China in Beijing's financial district.

The People's Bank of China's (PBoC) surprise cut to the reserve requirements of major banks is the latest sign of its shift towards more aggressive monetary easing, say economists who expect a lot more action in the coming months.

"A full RRR cut is generally viewed as the most blunt tool in the monetary policy tool box," Yu Song, economist at Goldman Sachs wrote in a note. "It sends a very strong signal of policy loosening."