city human rights officials warned this week .
it 's the latest salvo in an ongoing struggle between property developers to build or maintain rent-stabilized apartments alongside luxury units that go for thousands of dollars more a month .
other building have installed so-called ` poor doors ' for use by rent-stabilized tenants while full-rent residents get to use the front door .
dnainfo new york obtained pictures of the sign posted by property managers that warned only certain residents of the building were allowed access to the gym .