(Reuters) - British shopping centre operator Hammerson Plc said on Monday it won the backing of shareholder Elliot Advisors on its plans to sell more assets to cut debt and expand its board. The company, which sold assets worth 570 million pounds in 2018, said it would look to dispose more than 500 million pounds of assets in 2019, adding that it was in active discussions on deals with a total value of over 900 million pounds. The owner of Birmingham's Bullring and London's Brent Cross reported a 6.2 percent decline in net rental income to 347.5 million pounds for the year ended Dec. 31, as company failures hit occupancy at its malls. Hammerson said it plans to appoint two more non-executive directors in 2019 and establish an investment and disposal committee to oversee its divestments.