Two students from the Chinese University of Hong Kong (CUHK), who have participated in the Occupy Central movement , were denied entry to the Chinese mainland during Tomb-Sweeping Festival, Hong Kong-based Mingpao reported Sunday.Kwan Wai-hung, former vice president of the CUHK's students union, told Mingpao that he tried to enter Guangdong Province for the festival on Saturday but was rejected for "having participated in illegal activities and [his admission] may threaten national security."The Occupy Central movement was a months-long protest demanding political reform universal suffrage for the 2017 chief executive election.Kwan said that customs officers led him to a room, took away his ID card, checked his bag and took his pictures. After nearly an hour's wait, he was told he was forbidden from passing customs and should be back to Hong Kong.He said that he only helped organize negotiations for the movement and participated as an ordinary citizen, before he quit his position in the students union last year and was not active in the student federation either.Kwan added that he was worried that it might affect his employment prospects in the mainland and that he might not be able to visit the mainland in the next two or three years.Another former member of the CUHK's students union, Fung Sai-kit, was also denied entry the same day.Fung said that custom officers denied him entry into the mainland based on the regulations on exit and entry frontier inspection and sent him back to Hong Kong. He said that he plans to try to enter again during the summer holidays."For national security reasons, the local government is justified in denying their entry," Zhang Dinghuai, a professor at Shenzhen University, told the Global Times Monday.According to a survey conducted by the news portal sina.com.cn, 81.7 percent of 30,894 netizens voted to agree with the customs decision, with some saying that "everybody should pay for their mistakes."According to the Hong Kong-based newspaper Oriental Daily News in November 2014, one of the Occupy Central movement's organizers was rejected by customs officers in Shenzhen, Guangdong for having participated in activities that violate national security.During Tomb-Sweeping Festival, Hong-Kong based Wen Wei Po reported that the region saw a sharp drop in the number of visitors and in tourism and retail business due to the parallel-goods traders.The term "parallel-goods traders" refers to Chinese mainlanders who go to Hong Kong to buy cheaper products, such as infant formula and cosmetics, which they then sell at inflated prices.