Two former Taiwan presidents blasted a proposal by incumbent Ma Ying-jeou to pursue a peace treaty with China, warning it could cause the island to give up its sovereignty to the mainland.

"The peace treaty will be a surrender and unification treaty... Ma intends to turn Taiwan into a province of China," Ma's predecessor Chen Shui-bian, now in jail for corruption, said in a statement issued by his office on Wednesday.

Taiwan would be "relinquishing its sovereignty" as Beijing has insisted that the island must accept that there is only "one China", including Taiwan, as a precondition for the treaty, said Chen, who was president from 2000 to 2008.

Chen also cited Tibet as a failed example, saying its peace deal with China reached in 1951 was "a piece of waste paper" after an uprising eight years later that led to China's suppression and forced the Dalai Lama to flee.

Lee Teng-hui, who led Taiwan from 1988 to 2000, also questioned the goal of the treaty and urged "everybody to voice their opposition".

"Ma does not seek approval from parliament or the people's opinions. It's like Taiwan is returning to authoritarian rule," Lee, who oversaw the island's transformation to a democracy, said according to the United Daily News.

Ma on Monday suggested the island should consider a peace treaty with China within the coming decade, formally ending a civil war that has actually been over since 1949.

A peace treaty is widely considered one of the thorniest issues in the complex relations between China and Taiwan, reflected in Ma's reassurance that it would only happen if the island's people agreed.

He also dismissed concerns that a peace treaty is tantamount to a unification treaty.

China still claims the self-ruled island as part of its territory awaiting reunification, by force if necessary.

Ties were strained under Lee and Chen's rule due to policies promoting a separate identity for the island, but they have warmed since Ma took power in 2008 on a Beijing-friendly platform.