text: It emerged on Tuesday that BSkyB has been ensconced in a legal battle with Skype for more than five years.
  But the legal action over the "Skype" trademark only became public when Skype mentioned it in its 250-page initial public offering (IPO) document on Monday.
  A spokesman for Sky, which is 39.1pc-owned by Rupert Murdoch's News Corporation, said the company was trying to prevent Skype from using its trademark in relation to the sale of TV or internet service, because customer might assume that 'Skype' is part of Sky.
  "Sky is involved in a long-running dispute with Skype in relation to several trade mark applications filed by Skype, including, but not limited to, television-related goods and services," the spokesman said. "The key contention in the dispute is that the brands 'Sky' and 'Skype' will be considered confusingly similar by members of the public."
  Sky said its concerns were supported by consumer research.
  Last month, Sky's case for "trademark infringement" was upheld by the European Union's Office for Harmonisation of Internal Markets (OHIM), which ruled that Skype's trademark and its famous blue bubble logo were too similar to Sky's name and branding.
  Skype has said it will appeal the ruling to the OHIM's board of appeal and the European Court of Justice, if necessary. If Skype losses it may be prevented from using the Skype name or logo, without a licence.
  "These oppositions are based on BSkyB's claimed rights with respect to the mark 'Sky'," Skype said in its filing with the US Securities and Exchange Commission (SEC) to raise $100m (£64m) through an IPO.
  The SEC filing said the shares will be listed on New York's Nasdaq later this year. Luxembourg-based Skype did not state how many shares it expected to sell, or at what price.
  Sky said it has taken legal action against a string of companies for attempting to piggyback on the "Sky" brand.