The move comes days after Indonesian police said they had busted a sprawling $450 million cyber fraud ring targeting wealthy businessmen and politicians in China. 

Taiwan's foreign ministry said its deported nationals were among over 140 Chinese and Taiwanese suspects arrested in raids on July 29 in various locations including Jakarta, the city of Surabaya and on the resort island of Bali. 

In a statement the ministry said Jakarta had ignored Taipei's request that the Taiwanese suspects be returned to the island and instead sent them on Thursday to the mainland cities of Chengdu and Tianjin. 

"China continues to forcibly take Taiwanese to the mainland, completely ignoring our gestures of goodwill and appeal," the Mainland Affairs Council -- Taiwan's official body handling China relations -- said in a statement. 

"This is detrimental for investigation into cross-border crimes, and it also affects positive development of cross-strait relations," it said. 

The foreign ministry has also directed its Jakarta office to lodge a protest with the Indonesian government. 

The incident is the latest of several international deportations of Taiwanese suspects to China since Taiwan's President Tsai Ing-wen came to power last May.

Beijing distrusts Tsai, who has refused to recognise the island as part of "one China." 

China sees the island as a breakaway province to be brought back within its fold.

Under former China-friendly president Ma Ying-jeou, suspects would usually have been deported back to Taiwan as part of informal arrangements between crimefighting agencies in China, Taiwan, and countries where the fraudsters are operating.