Facebook boss Mark Zuckerberg has stonewalled calls for his company and Google to be regulated in the same way as mobile networks. Mobile chiefs said on Monday that the online companies should have to obey the same sort of strict rules as mobile phone businesses, because they are also used for communications, for example via Facebook´s messaging apps. However, Mr Zuckerberg refused to engage with the discussion other than to say that the issue was 'nuanced'. Scroll down for video . Founder of Facebook Mark Zuckerberg, who has refused to engage in discussion on whether Facebook and Google should be regulated in the same way as mobile phone networks . Instead, he used a 20-minute interview at a conference in Barcelona to insist again and again that he was 'not a regulator'. 'I don't really have much to say on that because I'm not a regulator…I'm not an operator and I'm not a regulator so I don't know what the regulatory framework should be exactly,' he said. When pushed on the point, he added: 'I don’t know. I’m still not a regulator.' Earlier that day, Tim Hoettges, the boss of Deutsche Telekom, which owns half of EE, told a conference in Barcelona that regulators need to clamp down on so-called 'over the top' companies - digital businesses like Facebook and Google which provide communications services on mobile and internet networks. 'There is a convergence between over-the-top web companies and classic telcos [telecommunications companies]. We need one level regulatory environment for us all,' he said. His call comes amid mounting concerns that internet businesses like Twitter, Facebook and Google can be used as a platform to publish pornography or hijacked by terrorist groups to radicalise new recruits. Many digital businesses have been slow to crack down on inflammatory material on their platforms, although they have vowed to get tougher in recent weeks. Google has started hiring Arabic speakers to help fight jihadi propaganda videos published on YouTube, its online video site. Speaking at the Mobile World Congress in Barcelona, Mr Zuckerberg insisted again and again that he was 'not a regulator' Facebook has said it will start doing more to tackle extremist propaganda. However, it has taken some of these companies years to take action, whilst others have failed to do anything. Earlier this month, it emerged that Twitter had snubbed a meeting with a government minister called to discuss ways to tackle the proliferation of pornography on certain websites. Around 500,000 explicit photographs and videos are published on social network every day, despite the fact that it is targeted at children as young as 13. Delegates at mobile world congress were disappointed with Mr Zuckerberg´s failure to engage with the regulation issue on Monday. People had spent up to two hours queueing to get a seat in the auditorium here the Facebook founder and chief executive was speaking. However, many left his session half way through as it became clear that he would not discuss the issue.
Mark Zuckerberg refused to discuss calls for Facebook to be regulated . Facebook chief insisted he was 'not a regulator' at a conference in Spain . Mobile networks have said online firms should have to obey rules like them . They argue social networks are also used for communication purposes . There are mounting concerns internet businesses are being used as a platform for porn and terrorism .