The mother of missing autistic teenager Yu Man-hon yesterday urged Chief Executive Tung Chee-hwa to show the same level of concern for her son as two Beijing officials did last month. Yu Lai Wai-ling said the frosty reception she had received from local delegates to the National People's Congress in Beijing last month was in comparison to the helpful attitude adopted by two public security officials she met. The officials said they had children of their own and would do their best to help find her son. 'Isn't it the case that our people's representatives have the responsibility to represent the people - Yu Man-hon's parents - to urge the relevant authorities of the Hong Kong Government to shoulder the full responsibility to locate Man-hon?' she asked. She has written a two-page letter to Mr Tung, all local NPC deputies and legislators urging the Government to take steps to co-ordinate efforts with mainland public security cadres to find her son. Last month, Tsang Hin-chi, a local member of the NPC Standing Committee, said it was hard for local deputies to assist Mrs Yu. But Mrs Yu said: 'The reality that I now face is that it remains unknown whether my son is still alive or not . . . I must urgently seek ways to trace my son.' She also rejected claims it was a waste of time and manpower to take her case to Beijing. Man-hon, who has a mental age of two, slipped through the Lowu checkpoint on August 24 last year after running away from his mother at Yau Ma Tei MTR station. He was returned to Hong Kong by mainland immigration officers but allowed back over the border again. Last night, a spokeswoman for the Chief Executive's office confirmed that they had received Mrs Yu's letter and had referred the case to the Security Bureau.