A SIGNATURE campaign is being held in Tsing Yi and Kwai Chung in protest against two top judges' suggestion that the possession of cannabis be decriminalised. The signatures, 1,000 of which have been collected, will be submitted to Executive Councillors on Tuesday. The campaign is jointly organised by the Association for Democracy and People's Livelihood, the Tsing Yi Concern Group and the Kwai Tsing Concern Group, following what they say were ''irresponsible comments'' by Mr Justice Kaplan and Mr Justice Godfrey. The pair's support for decriminalisation of cannabis, reported in the Sunday Morning Post, sparked criticism and support. Some legislators and government officials, including Commissioner of Police Eddie Hui Ki-on and chairman of the Action Committee Against Narcotics Professor Chen Char-nie, have said they are against such a move. But Executive Councillor Felice Lieh-mak, a psychiatrist, said she supported the suggestion, saying it would help control the usage of cannabis and undermine drug syndicates. Leung Kwong-cheong, chairman of Kwai Tsing District Board, said yesterday he feared more young people would be encouraged to take drugs if the law was eased. He said government figures showed most people taking cannabis were under 21. Yu Kwok Wai-ling, spokesman for Tsing Yi Concern Group, said drug abuse in the district had become serious. ''Some residents claim their water meters in the corridor are used by strangers to store heroin. ''From time to time little packets of white powder, which we suspect is heroin, are left in their water gauges in the morning but disappear in the afternoon,'' she said.