Updated at 6.22pm: Taipei Mayor Ma Ying-jeou revealed on Friday that ?friends? of Chief Executive Tung Chee-hwa had told to him cancel his visit to Hong Kong ? weeks before he was denied a visa by the Hong Kong government. The popular Taipei mayor had planned a visit to the city next week but was forced to cancel his trip when he was denied a visa on Tuesday. Hong Kong-born Mr Ma was invited by the University of Hong Kong to deliver two lectures and attend a seminar on culture and city management during his three-day visit. Speaking to reporters in Taiwan, Mr Ma confirmed reports he had been approached several weeks earlier by groups from Hong Kong. ?Whether they were sent by the Chief Executive I cannot say,? Mr Ma said. He added that the people were mutual friends of him and Mr Tung. They warned the mayor there might be changes to his itinerary, Mr Ma recalled. ?At least one group told me that it was related to my views of the anti-secession bill [in China],? he said. Mr Ma had been previously quoted as saying the proposed mainland law was unnecessary and unwise. He said another group told him to cancel his trip and say he was ?too busy with work??. ?I told them that a person of my status could not say something like this,? said Mr Ma. The government?s decision to deny Mr Ma a visa has sparked widespread criticism. The United States has expressed its concern, the Associated Press reported on Friday. Susan Stevenson, a spokeswoman for the US Consulate General in Hong Kong said: ?We believe the decision in this case was not a constructive one.? She declined to comment further. Senior officials in Taipei have said the incident could damage Hong Kong-Taiwan relations. Executive Yuan spokesman Chen Chi-mai said Taipei authorities would 'strongly protest' against the decision if Hong Kong did not provide a reasonable explanation. In Hong Kong, Liberal Party chairman James Tien Pei-chun said the decision would affect the territory?s image. He said this was because Mr Ma?s proposed visit was only to be an academic exchange, local media reported on Friday. Ronny Tong Ka-wah of the Article 45 Concern Group said Mr Ma?s visit did not pose any danger to Hong Kong or China. The government?s decision reflected a flaw in the territory?s immigration laws, he said. Legislators Emily Lau Wai-hing, of The Frontier, and Lee Wing-tat, of the Democratic Party, also said the incident would hurt Hong Kong?s international reputation and freedom of speech. Ms Lau and Mr Lee, along with other legislators met Secretary for Constitutional Affairs Stephen Lam Sui-lung on Friday to discuss the issue. Mr Lee told reporters that Mr Lam did not explain why the Taipei mayor had been denied a visa. However, Jasper Tsang Yok-sing of the Democratic Alliance for Betterment (DAB) said it was appropriate that Mr Ma did not come to Hong Kong. ?If the mayor comes now, it may spark a debate on the mainland anti-secession law,?? he explained. And a spokesman for the Chief Executive?s office said the government could not comment on individual visa application cases. He also declined to comment on whether the government had sent people to Taiwan to speak with Mr Ma. Mr Ma has said his friendship with Hong Kong people would not be affected by the incident. He previously visited Hong Kong in 2000 and 2001 ? when he was received by Mr Tung.