LONDON, July 29 (Reuters) - Britain’s Office for Budget Responsibility will publish new forecasts for economic growth and government borrowing on Oct. 27, finance minister Rishi Sunak said on Thursday. Sunak did not specify in his letter to parliament’s Treasury Committee if he would deliver a full annual budget or a planned multi-year review of government spending on the same date. (Reporting by David Milliken; Editing by Kate Holton) Our Standards: The Thomson Reuters Trust Principles.