Taiwan's Central News Agency said Chen was summoned over his alleged misuse of the discretionary state affairs fund and an alleged money-laundering case involving the former first family. Chen has denied the charges.
Xinhua, the official news agency of China which claims sovereignty over the island nation, reported Chen was arrested "for being involved in overseas money laundering and graft" and was questioned by prosecutors.
The CNA report said Chen, who led Taiwan before President Ma Ying-jeou, was quoted as saying while he may soon enter "Taiwan's Bastille," the prison would "only hold my body, not my heart."
The report said Chen asserted he is the top prisoner of war of Ma's ruling Kuomintang and the Communist Party of China since he remains "biggest hurdle for the two parties to move toward unification."
Ma came to power on a platform supporting closer economic and trade ties with the mainland.
China has threatened use of military force if Taiwan pursues independence. The countries have been ruled by separate governments for six decades.