Nigel Farage lashed out today after independent observers warned Labour's Peterborough by-election win was worthy of corrupt ex-Soviet state Kazakhstan.

The Brexit Party leader told MailOnline the constituency looked like 'another rotten borough' after his candidate was narrowly defeated earlier this month.

Election experts Democracy Volunteers have said the sight of people photographing their completed ballot papers was something they had only ever seen in Kazakhstan ‘many years ago’.

The oil-rich state has until recently had only one president since it broke with the Soviet Union in 1991, with claims that even last Sunday’s election was rigged.

Labour’s victory by just 683 votes over the Brexit Party in Peterborough was mired in controversy last week after The Mail on Sunday revealed claims that a convicted vote rigger was at the centre of the party’s campaign.

Cambridgeshire Police have since revealed they are investigating five complaints of electoral malpractice, including bribery.

Nigel Farage (pictured delivering a list of Brexit demands to No10 after the Peterborough by-election earlier this month) told MailOnline he feared the constituency was 'another rotten borough' after his candidate was narrowly defeated

Labour Party candidate Lisa Forbes reacts after winning the Peterborough by-election at the KingsGate Centre in Peterborough

John Ault, director of the organisation, said he had seen people photographing their completed ballot papers in what he suggested could show they were fulfilling a ‘contract’ to prove how they had voted.

He told The Mail on Sunday: ‘I have observed many elections across Europe and only once in Kazakhstan many years ago did I see what I saw happen three times in Peterborough.

‘There are signs up warning you not to take photographs and these were not selfies celebrating having voted but people photographing their cross on the ballot paper.’

John Ault, director of the organisation, said he had seen people photographing their completed ballot papers in what he suggested could show they were fulfilling a ‘contract’ to prove how they had voted

He added: ‘One can only speculate as to why some voters feel the need to do this, although this can, in some cases, point to a contract being fulfilled or an inducement having been given.

‘It needs to be discouraged and, in the cases I saw, they were either not noticed or not challenged by polling station staff.’

Mr Farage told MailOnline today: 'It's just endless isn't it. There's more and more and more of it.

'I think there is something inherently wrong with the entire postal voting process in this country.

'I think it's open to corruption, bribery intimidation, abuse. We've seen so many cases now where again and again we find - particularly in the inner cities - postal voting is producing the wrong results.

'And I'm afraid Peterborough looks like another one of those rotten boroughs.'

Democracy Volunteers sent a team of four experienced observers to observe 23 of the polling stations used in the by-election. They watched as about 700 of the 27,000 who voted at a polling station cast their vote and witnessed so-called ‘family voting’ – where more than one person goes into the same voting booth – in half of the stations.

The practice has in the past raised fears that voters were being told by other family members where to put their cross. Mr Ault said: ‘To the great credit of the polling staff, this was challenged persistently whenever it occurred. It is everyone’s right to vote in private.’

The concerns come after this newspaper revealed Tory claims last week that Tariq Mahmood, a convicted vote rigger, had been involved in Labour’s winning campaign.

The oil-rich state has until recently had only one president since it broke with the Soviet Union in 1991, with claims that even last Sunday’s election was rigged

He was photographed with Labour leader Jeremy Corbyn and successful Labour candidate Lisa Forbes last month.

Mr Mahmood admitted that he had canvassed for Labour but denied playing a bigger role.

Labour dismissed the Tory claims as ‘false and baseless’. But there were also concerns that almost one in three of the 33,998 ballots cast in the by-election were postal votes.

Wayne Fitzgerald, deputy leader of Peterborough’s Tory-run council, said: ‘The fact that concerns have been raised about family voting at polling stations shows just why it is important for the postal voting system to be changed. It is all too easy for pressure to be applied to people in the privacy of their homes.’

Three of the five complaints now being investigated by Cambridgeshire Police relate to postal voting.

Last night, a Brexit Party spokesman said: ‘All elections must be fair and seen to be fair – otherwise the whole system will be brought into disrepute.’