London ( CNN ) -- Britain 's Royal Mail has added nearly 14,000 extra rounds for its postal deliverers , hoping to clear a huge holiday backlog caused by winter weather woes . The service said it planned to complete 7,000 extra delivery routes Sunday , bringing packages , cards and letters to a million homes and addresses in an effort to catch up on deliveries during what it calls Britain 's coldest December in decades . About 6,500 extra deliveries were made last Sunday in the areas hardest hit by the severe weather , Royal Mail said . `` This is already the worst December weather the UK has seen for almost 30 years , '' Mark Higson , managing director of Royal Mail , said in a statement . `` We are planning up 7,000 delivery rounds this Sunday as we continue our drive to deliver items as quickly as possible . '' Online retailers are feeling the chill , too . Amazon.com 's UK service has halted taking orders for its special rush delivery option and recommends giving e-gift cards instead of packages . Retailer Marks & Spencer also said that it could no longer guarantee that orders placed now would arrive in time for Christmas , except for flowers . Royal Mail had previously announced plans to add up to 3,000 extra workers and 250 delivery trucks to brave the icy roads . It warned there 's little time left to get packages delivered . Tuesday is the deadline for first-class mail and packets that customers want to arrive in time for Christmas , Royal Mail said . CNN 's Brian Walker contributed to this report .
Royal Mail adds nearly 14,000 extra rounds for postal deliveries . Its director says the UK is experiencing the worst December weather in 30 years . Royal Mail is trying to catch up on the delivery backlog .