VETERAN legislator Hui Yin-fat repeated his threat of a private member's bill to force the Government to spend more of the Lotteries Fund on welfare services. He wants the fund to take 10 per cent of Mark Six proceeds instead of the present five per cent, which would cut the Government's share to 25 per cent. ''According to my own survey, the Hong Kong Government is drawing the heaviest lottery duty rate in the world,'' he said. ''Why does the Government always want to rob the poor?'' He said he would move a private member's bill if the Government did not amend betting duty laws to provide more cash for welfare. Mr Hui described Mr Patten's welfare proposals as piecemeal. He said the speech lacked a comprehensive plan to improve the livelihood of the whole population. Legco's labour sector representative, Tam Yiu-chung, criticised the Governor for citing technical difficulties as an excuse for delaying or even rejecting public consensus on a central provident fund. ''The most important thing for a retirement scheme is that it must be a soundly based system, and the Government should make some positive undertaking on this,'' Mr Tam said.