Trading in China’s much-anticipated Rmb40bn ($5.5bn) issue of special 30-year sovereign bonds was suspended twice on its market debut on Wednesday, as exchanges warned of “abnormal fluctuations” and urged investors to be rational and pay attention to the risks.

Beijing plans to sell a total of Rmb1tn 20 to 50-year sovereign bonds this year to fund government spending in critical areas as a way of trying to spur growth. The first batch of the bonds debuted on the Shanghai and Shenzhen stock exchanges, rather than just over the counter at banks, giving Chinese retail investors greater access than usual.

Prices for the new bonds, which offered a 2.57 per cent yield at launch, surged 13 per cent at the open before trading was suspended. They later jumped to a 25 per cent gain on the day before a second suspension by the Shanghai Stock Exchange.