Delta, the US's largest airline, has made an offer to buy the 49% of Richard Branson's Virgin Atlantic held by Singapore Airlines, according to the UK's Sunday Times and confirmed by The Wall Street Journal. The Sunday Times reports that Air France-KLM, Delta's European partner, could then buy part of Branson's 51% holding in Virgin. Rules say European airlines can't be controlled by non-Europeans, which is why Delta would team up with Air France-KLM to achieve control. Branson two years ago appointed Deutsche Bank to examine any offers for the airline, according to Reuters. And in Feb. 2011, Delta and Air France-KLM came close to a deal to buy Virgin Atlantic, but talks broke down over price and the Virgin brand, the Sunday Times reports. The Journal says Delta is after Virgin's slots at London's Heathrow Airport, the world's busiest hub for international traffic.