ATHENS, July 22 (Reuters) - Greece said on Thursday all unvaccinated restaurant and tourism workers nationwide must undergo regular COVID-19 tests, extending an obligation that previously applied only on some popular holiday islands as case numbers have continued to climb. After a disastrous year in 2020 where global travel evaporated, Greece lifted most restrictions and has been hoping for at least a partial revival of its crucial tourist industry over the summer. But following a renewed spike in COVID infections in recent weeks due to the spread of the more contagious Delta variant, Greece last week ordered testing twice a week for unvaccinated workers in restaurants and tourism companies on some of the country"s main holiday islands in an effort to save its summer season. read more The same rule will now apply to workers in these sectors across Greece, Deputy Citizen"s Protection Minister Nikos Hardalias told a weekly briefing. "Our aim is that our country continues to send the message that it has been and will remain a safe tourist destination." Despite recent restrictions, cases on the famed party island of Mykonos have spread quickly, forcing authorities last week to impose a nighttime curfew and ban music starting on July 26. Hardalias said that the situation in Mykonos has slightly improved and that authorities will decide on extending or lifting the measures in the next coming days. Alexis Tspiras, a former prime minister and head of the main opposition leftist Syriza party, said that restrictions enforced in Mykonos sent "a very bad signal" for Greece as a tourist destination. With a population of 11 million, Greece has inoculated about 45% of Greeks. After ordering the vaccination of healthcare and nursing homes staff, the government urged school teachers on Thursday to get the shot in time for the start of the school year in September. Greece reported 2,604 cases on Thursday, bringing the total to 469,042 since the pandemic broke out last year. Some 12,875 have died of COVID-related complications so far.