The DPP Central Standing Committee (CSC) yesterday decided to seek expulsion of Fan Chung-chung and Hsu Jung-shu for defying a party ban on members taking part in the forum, said party spokesman Cheng Wen-tseng.

The DPP's Central Advisory Committee (CAC) will hold a meeting on July 23 to make a final decision on the case, Cheng said.

CAC Chairman Chen Chin-teh said his committee will invite Fan and Hsu -- an ex-chairman of the Cabinet's Council of Agriculture and a former legislator respectively -- to defend themselves at the upcoming meeting.

Despite their rights to freedom of speech, Chen said Fan and Hsu violated the party rules by defying the party's clear order that no members would be allowed to attend the forum.

The forum was originally designed to be a meeting between officials from Taiwan's ruling Kuomintang and China's communist party. But it was renamed to accommodate the participation of DPP members.

The pro-independence party has been critical of what they call the government's pro-Beijing line although the DPP says it does not rule out some kind of engagement with China.

But the pair's participation in the forum has demonstrated dissent within the DPP camp over the pace of such engagement.

CSC member Wang Hsing-nan said the DPP has made it clear that party members are allowed to visit China on a personal capacity for non-political exchanges.

DPP legislative leader Trong Chai, a good friend of Hsu's, said he had called the former colleague three times trying in vain to talk her out of going to China.

The motion for the expulsion of Hsu and Fan was submitted to the CSC meeting by DPP Chairwoman Tsai Ing-wen.

Another DPP heavyweight, Su Tsung-hsiang, who heads the party's Hualien chapter, also went to China upon invitation by the forum's organizers.

But Su did not attend the forum, and his case will be reviewed separately by the CSC, the spokesman Cheng said.