SHANGHAI (Reuters) - China's central bank is injecting a combined 500 billion yuan (S$100 billion) of liquidity into the country's top banks, according to media reports, a sign that authorities are stepping up efforts to shore up a faltering economy.

Global shares and commodity prices rose on the reported move, although local money market rates climbed on the day, reflecting continued tightness in liquidity.

The Wall Street Journal, citing an unnamed Chinese bank executive, said the People's Bank of China (PBOC) is pumping in 100 billion yuan each into China's top five banks via standard lending facility in the form of 3-month loans.

When contacted by Reuters, a PBOC spokesman said: "We will make an announcement if we have any news."