A human rights watchdog is to ask Tung Chee-hwa to explain why a political activist and her young nephew allegedly were tailed by security officers when they attended the National Day show at the Hong Kong Stadium. Hong Kong Human Rights Monitor, which has received a complaint from activist Lui Yuk-lin, will also seek an explanation from the Urban Council, which manages the stadium. Ms Lui, a member of the April 5th Action Group, attended the celebration with her 10-year-old nephew last Friday after protesting during the flag-raising ceremony earlier in the day. She said they were followed around by six or seven security officers after entering the stadium. Ms Lui said they were even tailed when they went to the toilet. She said some of the officers were in plain-clothes and others were from the stadium's security team. She said she did not know if the plain-clothed officers who continued to follow them after they had left the stadium were police officers or security guards. Director of Human Rights Monitor Law Yuk-kai said: 'We hope Tung Chee-hwa and the Urban Council will check and explain the incident. 'It's an infringement on their freedom.' Ms Lui said her nephew was so scared by the experience that he had been reduced to tears at the stadium. 'He also has nightmares, shouting out in his sleep asking people not to follow him,' she said. Stadium manager Choy Chi-mun has denied sending security guards to follow Ms Lui and the boy. He said all their guards on duty last Friday were in uniform. Police said they had been in close co-ordination with stadium managers on security arrangements, but declined to comment on exact details.