Real estate group British Land has announced that social media giant Facebook has secured a number of new offices in London on its Regent's Place site.The US firm has signed an agreement for lease at 338 Euston Road and it will occupy the fifth floor of the building, as well as floors nine to sixteen and a ground floor events space, for a total of 66,000 sq ft.The newly-leased area will add to the 87,000 sq ft that Facebook currently occupies at Regent's Place, after it relocated their UK headquarters to 10 Brock Street."Facebook's decision to expand their presence at Regent's Place is a fantastic endorsement of the campus, and underlines their commitment to this location," said James Danby, head of office leasing at British Land.British Land shares were up 0.41% to 858.50p at 08:31 on Wednesday.