MILAN, Sept 27 (Reuters) - Telecom Italia (TIM) (TLIT.MI) will keep some of its offices closed as nearly 60% of the employees at Italy"s biggest phone company plan to continue working from home until Dec. 31, a union document showed. Companies and governments around the world are figuring out how to manage the return of staff to offices after the coronavirus outbreak forced them to reorganise work models and allow most employees to work remotely. Italy has made its COVID-19 "Green Pass" - a certificate showing someone has received at least one vaccine dose, tested negative or recently recovered from the virus - mandatory for accessing workplaces from next month. While the government is pushing public sector workers to return to offices armed with the Green Pass from Oct. 15, private sector firms have until the end of the year to adjust their remote working policies. TIM, which surveyed its staff about the matter, told unions that about 24,700 workers would continue working from home until the end of the year, according to the union document seen by Reuters. The former phone monopoly had roughly 43,000 employees in Italy as of June 30. "Based on these figures, TIM has decided not to immediately reopen all of its venues across Italy," the unions said in the document, citing a meeting with TIM representatives on Sept. 21. TIM declined to comment.