FLAT prices will increase further if the Government fails to speed up urban redevelopment, the Real Estate Developers' Association warned yesterday. The developers said urban redevelopment, which had been the greatest source of new land in the territory, would slow down by 1996 if the Government failed to work out new ways to help tackle the difficulty of land resumption. Chairman of the Real Estate Developers' Association Thomas Kwok said yesterday at the Legco Lands and Works Panel that the supply of urban new flats would decrease to a low level by early 1996. ''Most of the lands that are easy to resume will have been developed by that time and there will be no major piece of lands left in the urban areas,'' Mr Kwok said. The Government would clearly fail to hit its set target of producing 35,000 units per year after 1995. He warned that flat prices would continue to soar if the Government failed to address the issue. Mr Kwok urged the Government to amend the Crown Lands Resumption Ordinance to help developers resume lands from small owners. The association proposed that developers be allowed to pay the Housing Authority the construction cost for a number of public estate units to rehouse affected tenants. United Democrats legislator James To Kun-sun said he would move a motion of no confidence on the Government's urban redevelopment policy and might ask Secretary for Planning, Environments and Lands Tony Eason and his deputy, Canice Mak Chun-fong, to resign. Mr Mak said the Government was not dodging the matter, stressing that six months was needed before a review of the complicated matter could be complete. He said the Government was considering an amendment to the ordinance whereby developers resumed land if they could provide affected tenants with a satisfactory rehousing arrangement.