Eight more Taiwanese nationals have been arrested in Cambodia over an alleged telephone scam, police said Tuesday, with China apparently poised to send a plane to collect them despite fierce opposition from Taipei.

Taipei accuses Beijing of "abducting" its citizens from countries that do not recognise the island's government -- such as China ally Cambodia.

A total of 21 Taiwanese and 14 Chinese have now been arrested in Cambodia over recent days for allegedly running a telephone fraud targeting victims on the mainland.

"We will deport them to China this week. China will send a plane to pick up all of them," Major General Uk Heisela, director of inspection and procedure at the General Department of Immigration, told AFP.

In April both Malaysia and Kenya returned Taiwanese nationals accused of crimes to mainland China sparking uproar in Taipei.

Uk Heisela said the eight new arrests were made on Saturday in a raid in Phnom Penh.

Cambodia, historically one of Beijing's closest allies in Southeast Asia, refuses to draw a distinction between China and Taiwan, simply referring to nationals from the latter as "island Chinese".

Taiwan is self-ruling after splitting with China in 1949, following a civil war, but Beijing still sees it as a part of its territory waiting to be reunified.

The island has never formally declared independence.

Observers read the deportation cases as a Chinese bid to pressure Taiwan's new government -- which took office in May.

Beijing does not trust the traditionally pro-independence ruling Democratic Progressive Party (DPP).

Taiwan insists citizens deported from third countries should be returned to the island and not to mainland China.

On Monday Taiwan's Mainland Affairs Council, which handles affairs with Beijing, said the deportations are a setback for ties.

Taiwan's new president Tsai Ing-wen has repeatedly pledged to maintain the "status quo" with Beijing.

But she also has not bowed down to pressure to accept Beijing's definition of cross-strait relations.

Taipei says its emissaries have been unable to reach the arrested suspects in Cambodia.