LONDON — Britain deployed 1 200 more soldiers to secure the Olympics yesterday, as embarrassed organisers scrambled to fill a shortfall left by a private firm hired to guard the Games just three days before the opening ceremony.

Police stressed, however, that they were content with security arrangements for the greatest show on earth, which kicks off in Cardiff in Wales today with a soccer match between the women’s teams of Britain and New Zealand.

Hundreds of thousands of visitors have descended on London from around the world and a million extra people are expected in the city every day of the July 27-August 12 event, putting pressure on a creaking transport system some of which dates from the 19th century.