LONDON (Reuters) - Britain's cyber security body urged organisations to install the latest Microsoft Exchange Server updates as a matter of urgency on Friday, after the company became aware of flaws that have led to large-scale access to the email server. "We are working closely with industry and international partners to understand the scale and impact of UK exposure, but it is vital that all organisations take immediate steps to protect their networks," said Paul Chichester, director for operations at the National Cyber Security Centre. (Reporting by Paul Sandlel writing by Kate Holton; editing by Michael Holden)