China on Friday threatened to impose the death penalty in extreme cases for "diehard" Taiwan independence separatists, a ratcheting up of pressure even though Chinese courts have no jurisdiction on the democratically governed island.

China, which views Taiwan as its own territory, has made no secret of its dislike of President Lai Ching-te who took office last month, saying he is a "separatist" and staged war games shortly after his inauguration.

Taiwan has complained of a pattern of ramped up Chinese pressure since Lai won the election in January, including ongoing military actions, trade sanctions and coast guard patrols around Taiwan-controlled islands next to China.