Aug 31 (Reuters) - Alphabet Inc-owned (GOOGL.O) Google is extending its voluntary return-to-office policy through January next year, CEO Sundar Pichai said on Tuesday, citing uncertainty caused by the COVID-19 pandemic in many parts of the world. The rapid spread of the highly contagious Delta coronavirus variant is also making companies reconsider their mask mandates and vaccination policies. "Beyond January 10, we will enable countries and locations to make determinations on when to end voluntary work-from-home based on local conditions," Pichai said in an email to employees. In the last few weeks, companies including Amazon.com Inc (AMZN.O) and Lyft (LYFT.O) delayed their return-to-office timelines to 2022 for U.S. workers due to the pandemic. read more Google had earlier delayed its return-to-office policy from September to October. It was one of the first companies to ask its employees to work from home due to the health crisis.