Eighty-six countries have announced their support for a ban on ozone-destroying chemicals by the year 2000 and are calling for an international fund to help Third World countries join in the effort.

The resolution adopted Tuesday at the U.N.-sponsored conference stepped up the timetable of the 1987 Montreal Protocol, which requires industrial nations to halve production of the chemicals by the end of the century.The draft declaration says developing countries should be helped in finding and financing alternatives to the most damaging of such chemicals - chloroflourocarbons.

CFCs are used in refrigerators, air-conditioners, food containers, foam insulation and padding, aerosol cans and other industrial products.