LONDON—Amazon said on Tuesday it has started recruiting for 20,000 seasonal positions across the United Kingdom to cover upcoming peak trading times, which include Christmas, joining a battle for temporary workers in a tight labor market. The group, which has 55,000 permanent UK employees, said the temporary jobs would be in its network of fulfillment centers, sort centers and delivery stations. Amazon UK said pay for operations roles would start at a minimum of $13.68 an hour, rising to $15.32 an hour in some parts of the country—rates in line with a pay rise given to permanent employees in June. The group is also looking for people to deliver parcels in their spare time for between $17.59 and $20.29 per hour. Reuters reported on Monday that warehouses in Britain are having to pay up to 30 percent more to recruit staff after a chronic shortage of workers exacerbated pressure on …