SHANGHAI, May 22 (Reuters) - The first batch of China's 1-trillion-yuan ($138.14 billion)ultra-long special treasury bonds, which debuted on Wednesday, surged 25% in the early session on the Shanghai stock exchange, triggering trading suspensions.

The 30-year sovereign bonds jumped more than 13% at the open, prompting a 30-minute suspension by the Shanghai Stock Exchange, which cited "abnormal fluctuations" and urged investors to be rational.

Trading was suspended again until late afternoon after the bonds shot up 25%.

"It shows bullish sentiment," said Wang Hongfei, a bond trader. "Investors trade the bonds in the same way they trade stocks."

Retail and institutional investors are also allowed to participate in the exchange, where bond trading is typically thin and causes prices to jump on any small money flows.

China plans to sell 1 trillion yuan of special treasury bonds this year - with tenors of 20, 30 and 50 years - as Beijing ramps up support for a slowing economy.

The first batch of the special treasuries started changing hands in China's interbank market on Wednesday. The bonds also trade on the Shanghai and Shenzhen stock exchanges, as well as on the so-called OTC bond market, allowing individuals to participate via bank outlets. ($1 = 7.2388 Chinese yuan renminbi) (Reporting by Shanghai newsroom; Editing by Christian Schmollinger and Shri Navaratnam)