LONDON, June 16 : The chief executive of Vodafone urged European governments to speed up regulatory changes to allow mobile phone groups to develop the scale to drive the investment needed to keep up with the United States and Asia. "I think speed is always the challenge, and the faster the better," Margherita Della Valle told the Reuters Next summit in London on Tuesday, referring to an EU consultation on merger guidelines. "Well-invested digital infrastructure is the right thing, not just for our economies, but also, frankly, for security and resilience in the current geopolitics. And if we want this, we need more investment, which needs scale."