Tom Glocer, chief executive of Reuters, last night insisted customers were "overwhelmingly" in favour of an agreed merger with rival Thomson Corporation as European regulators said they had opened an in-depth investigation into the combination over competition fears.

The $17.4bn (€12.4bn) deal to combine Thomson, the electronic data provider that was once among the world's largest publisher of newspapers, and London's Reuters faces regulatory delays in both the US and Europe, although the EU regulator's new commissioner is unlikely to block the pact.