Emails sent to the Big Pictures agency in 2010 and 2011 contained the flight details of dozens of celebrities, including Madonna, Princess Beatrice and Sienna Miller.

Richard Branson's airline Virgin Atlantic is under mounting pressure to explain how an insider was apparently able to pass the confidential flight details of as many as 70 celebrities to a major paparazzi agency. Emails sent to the Big Pictures agency in 2010 and 2011 contained the flight details of dozens of celebrities, including Madonna, Princess Beatrice and Sienna Miller. Some of the figures alleged to be affected are friends of Sir Richard and his family and the allegations could prove hugely embarrassing for the tycoon, who is known for his close ties to the world of show business. A senior employee is understood to have resigned on Thursday after initial allegations that she passed on the flight details of eight celebrities including the singer Cheryl Cole and her former husband, the Chelsea footballer Ashley Cole, singer Robbie Williams and actress Scarlett Johansson. The airline launched an internal investigation and insisted it had "robust processes in place to ensure that passenger information is protected". But yesterday another cache of emails came to light that suggested that dozens more famous passengers may have been subject to the privacy breach. Emails seen by the Press Gazette contained the flight details of dozens of celebrities ranging from film stars Charlize Theron and Kate Winslet to Top Gear presenters Jeremy Clarkson and James May. The emails, sent over several months, suggest a degree of familiarity between the two correspondents. In one, Big Pictures allegedly wrote to the Virgin insider, understood to be a supervisor of Upper-Class passengers, saying it was "trying to sort you out some money with accounts". One email, reportedly containing details of a return flight from Heathrow to Newark taken by Borat actor Sacha Baron Cohen and his actress wife Isla Fisher, included the comment: "They're in economy!!!!!!" Big Pictures also appears to have been given an anonymous tip-off about a flight taken by people referred to as "Madonna's kids". In a statement issued on Thursday, Virgin Atlantic called the allegations "extremely serious" and said it had launched an immediate investigation. Virgin Atlantic's spokeswoman could not confirm whether Virgin Group chairman Richard Branson would be personally apologising to the celebrities affected and refused to comment any further pending the outcome of an investigation. The allegations are hugely embarrassing for an airline that markets itself as a glamorous alternative to other long-haul carriers and is known to be popular with the rich and famous. Branson is yet to comment publicly. Others who appear to have been affected include Rihanna, Russell Brand, Rob Brydon and Jonathan Ross. Legal experts said that such disclosures may not be a criminal offence. However, solicitors for Ashley Cole and Sienna Miller said they were taking legal instructions over the allegations. No representative of Big Pictures, owned by the former Celebrity Big Brother contestant Darryn Lyons, was available to comment.