Electoral Commission investigations must be limited to a year, Whitehall standards chief says telegraph.co.uk - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from telegraph.co.uk Daily Mail and Mail on Sunday newspapers.
The Labour Party has written to the Chief Executive of the Electoral Commission to call for an "urgent investigation" into donations received by the Conservatives.
Boris Johnson is facing an investigation by a watchdog the Tories have been trying to axe, having long accused the organisation of being biased and unfairly targeting pro-Brexit campaigners.
The Electoral Commission s critics are now seeking to have it abolished and replaced after a series of scandals including its lengthy investigation of numerous Vote Leave officials.
The quango was especially criticised for its efforts to prosecute pro-Leave activists Alan Halsall and Darren Grimes, which ended last year in police dropping its investigations following discussions with the Crown Prosecution Service.
The case of Mr Grimes, founder of pro-Brexit campaign group BeLeave, who was initially fined £20,000 for allegedly making false declarations over donations, sparked particular anger and resulted in him winning an appeal against the penalty.