TAIPEI (AFP) - Taiwan issued a protest to Beijing on Thursday (Aug 3) over a decision by Indonesia to deport 22 Taiwanese fraud suspects to China, the latest such deportation to hit the island amid frosty cross-strait ties.

The move comes days after Indonesian police said they had busted a sprawling US$450 million (S$600 million) cyber fraud ring targeting wealthy businessmen and politicians in China.

Taiwan's foreign ministry said its deported nationals were among 143 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 to the mainland cities of Chengdu and Tianjin on Thursday.

"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.

Indonesian authorities declined to specify the suspects' nationalities.

"This morning we sent back 143 people who were suspected for cybercrime using two planes to China," immigration spokesman Agung Sampurno told AFP.

"(They) have been sent back using emergency travel document issued by the Chinese embassy, so logically they are Chinese," he said, adding the planes the suspects were put on were prepared by the Chinese government.

Taiwan's foreign ministry said it had 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.

Just last week, Cambodia deported seven Taiwanese suspects implicated in another telecoms fraud case to China.

In February, Spain sent more than 200 Taiwanese suspects to China despite Taipei's protest.