SAN FRANCISCO (Reuters) - The recovery of the Antarctic ozone hole may be delayed until 2065 because reservoirs of ozone-destroying chemicals may be larger than anticipated, according to research presented on Tuesday.

Ozone in the upper atmosphere blocks harmful ultra-violet rays and scientists expect the ozone layer will heal itself in the absence of large chemical emissions.

Researchers speaking at an American Geophysical Union meeting said reservoirs of the chemicals in developed countries may be larger than initially thought and their emissions may postpone a recovery of the ozone hole to 1980 levels.

Scientists had expected a recovery to those levels by about 2050 following the 1987 Montreal Protocol that banned the production of the chemicals. Researchers said they now expect a recovery may not occur until 2065.