Taiwan's mainland affairs chief resigned on Tuesday, after he admitted forcing his former deputy to quit in August last year over allegations that he had leaked official secrets.

At the press conference Wang Yu-chi said he felt sorry for the social turmoil caused by the case involving former mainland affairs deputy chief Chang Hsien-yao.

Wang's resignation came shortly after Taipei prosecutors said earlier Tuesday that they would not indict Chang for allegedly leaking secrets to the Chinese mainland due to insufficient evidence.

Taiwan's mainland affairs office said last year Chang left his post for "family reasons."

Chang later said he was forced to do so.

"He was not charged because there was not enough evidence to show he leaked information," the Taipei District Prosecutors Office said in an earlier statement.

Expressing his disappointment, Wang said that while he disagrees with the prosecutors' view he has no choice but to respect it.

Wang was supposed to meet Zhang Zhijun, the head of mainland China's State Council Taiwan Affairs Office, from February 7 to 8 in the island to exchange opinions over cross-Straits cooperation.

However Zhang postponed his visit last week over the TransAsia plane crash that killed at least 40 passengers.

Wang said on Tuesday that he hopes the two offices would continue to communicate despite his resignation.

Wang and Zhang met on February 11, 2014 and it was the first meeting between the offices in 20 years since their establishment.