EU anti-trust chiefs said Wednesday they have asked five European telecoms giants to answer concerns over possible industry collusion. A European Commission spokesman told AFP it had sought answers on "conditions of standardisation for future mobile communications services," following what the Financial Times said was periodic meetings since 2010 between bosses of France Telecom, Deutsche Telekom, Telecom Italia, Telefonica and Vodafone. No formal investigation has been launched at this stage, stressed Antoine Colombani, spokesman for European Union Competition Commissioner Joaquin Almunia. The spokesman said the mobile industry association, the GSMA, had also been contacted. Such requests usually signal the preliminary stages of more detailed probes. One source close to the case said questions focused notably on advertising platforms conceived for smartphones, or payment services via mobile phones. The Commission is responsible for ensuring transparency across markets. According to the FT, the so-called "E5" meetings addressed topics that included challenges posed by US groups such as Google and Apple and harmonisation of technology platforms.