Share prices on mainland China’s two principal stock markets continued to fall yesterday evening despite renewed intervention from the authorities to try to stop the slide. The Shanghai and Shenzhen markets closed 5 percent and 3.3 percent lower respectively overnight.

Within minutes of the market opening the Shanghai Composite Index fell by more than 8 percent - while the Shenzhen Component took a 5 percent hit.

After ten minutes more than 1,000 companies' shares were down by 10 percent - when shares fall by this much companies are automatically suspended from the market.

The sharp downturn has continued despite direct intervention to buy shares by the People’s Bank of China – the Chinese Central Bank and the fact that up to 50 percent of all stocks are now suspended on both markets.

Commentators are divided on the possible impact on the wider global economy if the slide goes on.

The investors being burned comprise principally millions of new Chinese retail or smaller shareholders, but with the Chinese economy slowing below its target 7 percent for the first time in a decade, any impact on consumer demand and corporate confidence could have global impact.

One upside perhaps is a further fall in oil prices. The key price benchmark for Brent Crude fell a further 2 percent yesterday to $55.40 following a slide of 6 percent on Monday.

The price of oil is now more than fifth lower than its near $70 current year high in mid-May – also impacted by Greece and the prospect of a nuclear deal with Iran leading to new supplies of oil from that country.