The head of the UK’s elections watchdog has called for urgent reform of electoral laws and confirmed an inquiry has begun into possible Russian interference in the Brexit vote.

Sir John Holmes, chair of the Electoral Commission, said major changes were required to the current regime in order to told politicians and campaigns to account.

Sir John said: “We must avoid complacency to stop a perfect storm from forming which would put our democratic processes in peril.”

He set out a number of proposals, including rules requiring campaigners to reveal themselves in online advertising, in a bid to deal with Russian interference in elections.

Another proposal would see higher fines for political parties in breach of spending laws or that fail to declare their funding sources.

The commission is already conducting inquiries into Leave.EU and Vote Leave.

Sir John said the commission was also speaking to tech giants about Russian involvement in the referendum.

He said: “We are talking to Google, Twitter and Facebook and others about what they know about interference there might have been from the outside … They have promised to by the middle of this month.”