LONDON (Reuters) - There is “absolutely no evidence” that outside forces such as Russia used Facebook to target users and influence Britain’s vote to leave the European Union, the world’s biggest social network said on Monday.

Nick Clegg, head of global affairs at Facebook and Britain’s former deputy prime minister, said the network had run two full analyses of its data held in the run up to the 2016 referendum and found no evidence of a significant attempt by outside forces to influence the outcome.

Opponents of Brexit have repeatedly questioned whether the Kremlin played a role in the vote by promoting stories online on issues such as immigration in a bid to sway opinion. Britain has said it found no evidence that Russia interfered in the vote and Moscow has repeatedly denied even trying.

Clegg, deputy prime minister from 2010 to 2015 and a strong campaigner to remain in the European Union, said the roots of British Euroscepticism existed long before Facebook launched, and had for many years been driven by traditional media.

“Much though I understand why people want to sort of reduce that eruption in British politics to some kind of plot or conspiracy - or some use of new social media through opaque means - I’m afraid the roots to British Euroscepticism go very, very deep,” he told BBC Radio.

A consultancy firm Cambridge Analytica has also come under scrutiny over its role in the 2016 referendum after it obtained data from millions of Facebook users without their permission. It was hired by Donald Trump for his 2016 U.S. presidential election campaign.

Clegg said any claim that that data was used in the Brexit referendum was also false.

He is due to give a speech later on Monday about possible regulation of social media and the internet.