Feb 12 (Reuters) - UK real estate investment trust Tritax Big Box has reached an agreement for a possible all-share offer for rival UK Commercial Property REIT Ltd (UKCM) valued at 924 million pounds ($1.17 billion), the companies said on Monday.

Under the terms of the possible deal, every UKCM owner will get 0.444 new Tritax shares for each share they hold. The companies are poised to have a combined market capitalization of 3.9 billion pounds.

Tritax owns warehouses and counts companies such as Amazon and Ocado as customers, while FTSE 250-listed UKCM invests in shopping centres, office buildings and distribution centres.

($1 = 0.7915 pounds) (Reporting by Eva Mathews in Bengaluru; Editing by Savio D'Souza and Rashmi Aich)