THE United Nations High Commissioner for Refugees (UNHCR) yesterday urged the Government to step up forced repatriation, and warned non-refugees to return home before cash incentives were cut. Chief of mission Robert Van Leeuwen also gave the strongest indication yet that the UNHCR planned to scale down its presence in Hongkong. He recently denied reports that he had said the UNHCR would pull out. Yesterday he said that the UN's Comprehensive Plan of Action to address the influx of boat people over the past 18 years had reached a new phase with the decreasing number of genuine refugees. ''There is no thought at the moment of eliminating [the UN presence] altogether, but we may need to reduce it sharply in line with our own approach to non-refugees in the detention centres.'' The UNHCR is responsible for voluntary repatriation and the Government is responsible for forced or mandatory repatriation. Mr Van Leeuwen joined 265 voluntary returnees on a flight to Hanoi yesterday. Before boarding, he said countries in the region were rethinking their approach. Everyone preferred voluntary repatriation, but now recognised the detrimental effects of life in detention. ''Everyone realises that certain actions have to be taken to bring this problem to an end quickly within the humanitarian framework. ''We hope to spearhead that effort from Hongkong for the simple reason the process started in Hongkong one year before the Comprehensive Plan of Action was adopted''. The UNHCR has been in Hongkong since 1957, and expanded after the first Vietnamese asylum-seekers arrived in 1975. Mr Van Leeuwen urged the Government to ''negotiate with the Vietnamese Government a wider pipeline for the orderly repatriation programme''. Forced repatriation of non-refugees is determined by the British, Hongkong and Vietnam Governments. At present, Vietnam's reception centres have a maximum capacity of about 300 returnees and take three or four days to process those who return. Mr Van Leeuwen advised boat people to go home before the US$50 (about HK$390) departure incentive and the US$30 a month for 12 months on arrival were slashed. The UNHCR would advise donor countries to redirect aid for boat people from Hongkong to projects in Vietnam, and would seek substantial cuts in grants to those returning. Security panel convenor Elsie Tu said she would call for more mandatory repatriation flights at the panel meeting on Tuesday. Eight mandatory flights have been scheduled for this year compared with five last year, but an official source said the increase could be limited by the maximum capacity of Vietnam's reception centres. Others said the Government was held back by fears of international criticism. Mrs Tu said she was not advocating violence. ''But this has been happening all over the world and we have already been more humane than most countries. The children particularly have a right to be free, rather than staying just because their parents want them to.'' Government refugee co-ordinator Brian Bresnihan said the present rate of return could close the boat people camps by 1996. The UNHCR was expected to stay ''with an adequate personnel for as long as the vietnamese migrants are here'', he said. Mr Van Leeuwen said voluntary repatriation was expected to rise to 800 this month after dropping to 550 last month. Security branch statistics showed 38,233 boat people remain in the camps.