The row over security during Vice-Premier Li Keqiang's visit to Hong Kong deepened yesterday as lawmakers and students rejected an account given by Police Commissioner Andy Tsang Wai-hung and said he should resign if it was found he was not telling the truth. Tsang was asked to explain two incidents which some lawmakers say have raised questions about authorities' respect for freedom of expression during the high-ranking Beijing official's visit to the city. During the meeting, which ended with a lawmaker throwing a T-shirt into Tsang's face, security panel lawmakers also questioned his explanation of police officers' actions. Responding to criticism of police blocking a Now TV camera during an arrest at Laguna City in Lam Tin on August 16, Tsang said the officer had reacted out of 'basic instinct' when he saw a 'black object' and had stopped his action as soon as he realised it was a journalist's camera. The police chief also said three students detained at the University of Hong Kong on August 18 had sworn at police and campus security guards and that officers had only been helping the university to prevent them from entering a secure area. But Now TV said it had footage that would show Tsang's remarks regarding these incidents were 'against facts', and Democratic Party lawmaker Lee Wing-tat said the police chief's claims were untrustworthy. 'He appeared to be making things up to cover police mistakes,' said Lee. 'If Tsang is found to be lying, he should resign.' Describing the officer's actions in Lam Tin as 'basic instinct', Tsang said: '[He] felt a black shadow with a black object approaching so he used his hand to block it. His hand then got stuck on the camera and he asked the reporter: 'Can I take my hand back?'' Now TV vice-president Annie Cheng Lai-king disputed this. 'Our colleagues were hindered by a man in blue vest and then another man in a suit, who pushed our camera,' she said. Civic Act-up lawmaker Cyd Ho Sau-lan and pan-democrat Lee Cheuk-yan called for more details. Describing events when Li visited the university for its centenary celebration, Tsang said the three detained students had been taken to a staircase in the K. K. Leung building to help the campus guards. 'We were only assisting the school to prevent the students entering a security area ... the officers and guards demanded that they leave but they refused,' he said. 'They swore at the officers and travelled back and forth in the staircase. There is no basis to say it is false imprisonment.' One of the detained students, Samuel Li Shing-hong, denied that they had sworn at the police. The university, which did not send a representative to the Legco meeting, said it had not been informed of any plans for a secure area. As the meeting drew to a close, People Power lawmaker Wong Yuk-man threw a T-shirt with a June 4 pro-democracy motif into Tsang's face. Panel chairman James To Kun-sun said the panel would discuss the incident at its next meeting.