Paul Nuttall has had to move house because of fears for his personal safety, Ukip has said.

The party leader's home address was published on social media after he was accused of election fraud over allegations he gave the wrong address when registering to stand in the Stoke-on-Trent Central by-election.

Ukip's chairman Paul Oakden said there had been a series of “concerning incidents” at the Stoke property. He added that the election returning officer had been informed.

It emerged earlier this month that the house had been declared as Mr Nuttall’s address in his nomination papers for the byelection, before he was resident there. The Electoral Commission’s guidance for candidates says those standing in Westminster elections must give their current home address on their nomination papers; this cannot be just a business address. Mr Nuttall filed his papers on 31 January.

But in a series of tweets during a visit to the property on 1 February, Channel 4 News political correspondent Michael Crick published images of the empty property, without any furniture inside.

It is a crime in the UK to supply false information to the Electoral Registration Officer, and Staffordshire police have said they are investigating after receiving a report of an allegation of election fraud.

Ukip have previously stated that the party is "entirely happy that all the rules have been complied with".

Mr Oakden said: “Since the address of the house Paul Nuttall has been staying at during the Stoke-on-Trent Central campaign was published on social media there have been a series of concerning incidents at or around it.

”The most serious of these was two unknown men attempting to gain access to the house through a rear entrance.

“There has also been hate mail posted through the letter box and other intrusive behaviour including trespassing in the private garden of the premises and attempts to take pictures through windows and the letterbox.”

Ukip is hoping to take the Stoke Central seat from Labour on 23 February.

Labour has held the seat since 1950 but Ukip, who came second in the 2015 General Election by 4,000 votes, is considered a strong contender.

More than two thirds of people in the constituency voted to leave the EU in the referendum last June.

Clive Lewis, the shadow Business Secretary, said there are “swathes of the country, like in Stoke, where we are hanging on by the fingernails to keep Ukip at bay.”

The Labour Party has also launched an apparent 'attack ad' against Mr Nuttall, in another move that signifies they consider him a real threat.

Labour leader Jeremy Corbyn tweeted the video about Mr Nuttall with the warning: “Voters of Stoke, if you value your NHS then don’t vote for this man who wants to sell it off #CarefortheNHS.”

In the footage, MEP Mr Nuttall brands the NHS “a monolithic hangover from days gone by”.

In pictures: Local elections 2016 Show all 10 1 /10 In pictures: Local elections 2016 In pictures: Local elections 2016 Mayor of London Boris Johnson and wife Marina leave after casting their votes at a polling station in Islington, north London PA In pictures: Local elections 2016 Northern Ireland First Minister, Arlene Foster (C), Rhonna McMahon (R) and Paul Robinson leave after casting their vote for the Assembly Election, at Brookeborough Primary School in Enniskillen, Northern Ireland Reuters In pictures: Local elections 2016 Labour party leader Jeremy Corbyn arrives to cast his vote at a polling station in Islington, north London PA In pictures: Local elections 2016 David Cameron and Samantha Cameron cast their votes in the London Mayoral Election in London Getty Images In pictures: Local elections 2016 Labour Party Mayoral candidate Sadiq Khan and his wife Saadiya pose outside The Richardson Hall St Alban's Church Centre in Streatham after casting their votes in London's Mayoral and Assembly elections Getty Images In pictures: Local elections 2016 Britain's Conservative party candidate for Mayor of London Zac Goldsmith and his wife Alice leave after voting at a polling station in the Barnes suburb of south west London AP In pictures: Local elections 2016 George Osborne casts his vote in the London Mayoral Election in London Getty Images In pictures: Local elections 2016 SNP supporter Trish Traynor outside a polling station at St Ninian & Triduana RC Church in Glasgow as the polls open in the Scottish Parliament election PA In pictures: Local elections 2016 Scottish Labour leader Kezia Dugdale (right) with partner Louise Riddell outside a polling station in Edinburgh after casting her vote in the Scottish Parliament election PA In pictures: Local elections 2016 SNP leader Nicola Sturgeon with her husband Peter Murrell after casting her vote at Broomhouse Community Hall polling station in Glasgow as Scotland goes to the polls in the Scottish Parliament election PA

The by-election was triggered by the resignation of Tristram Hunt, who is to become director at London's Victoria and Albert Museum.

It is being held on the same day as the Copeland by-election, sparked by the resignation of Labour's Jamie Reed.