Two of the world's largest retail real estate companies, Australia's Westfield and US developer Simon Property Group, have declared stakes in Liberty International, strengthening the prospect of a bid for the FTSE 100 retail property owner.

Westfield, an Australian shopping centre developer, said it had built a stake of just less than 3 per cent in Liberty, which has a £3.4bn market value and owns parts of Covent Garden and Earls Court in London, as well as centres such as Lakeside in Thurrock.