The electoral system is close to breaking point and the mayoral and local elections on Thursday are vulnerable to large-scale fraud, Gordon Brown is warned today.

Efforts to improve turnout by increasing postal voting have raised the risk of fraud and undermined confidence in the electoral process, a damaging report from the Joseph Rowntree Trust concludes.

The report criticises the state of the country’s electoral registers, which often include voters who are dead, fictitious or have a vote registered elsewhere. In some areas, particularly those with many migrants, up to a third of eligible voters may be missing from the roll.

The trust calls for an urgent overhaul, including making voters show photographic ID to get a ballot paper. It also calls for the cleansing of electoral registers to ensure that all names are legitimate. Thousands of “phantom” voters have just been removed or have disappeared from the register in Peterborough after the council drew up a new electoral roll.

The Electoral Commission has repeatedly demanded tougher laws to improve integrity. The Council of Europe said in January that British elections had become “childishly simple” to rig. The Government is resisting further reforms.

“It is very concerning that ministers tend to focus on ‘quick fixes’ to solve declining turnout and ignore genuine concerns about how easy it is to cheat the system,” the report’s author, Stuart Wilks-Heeg, says.

The document claims the Government has effectively turned a blind eye to electoral fraud, dismissing evidence as largely anecdotal.

The Times exposed allegations of widespread postal vote rigging in the 2004 local and European elections but Labour waited until it had won the 2005 general election before acting. Its Electoral Administration Act 2006, which introduced modest changes, is described by the trust as having “proved deficient in combating electoral fraud”.

Three men, including a former mayor, were jailed in Peterborough this month for attempted postal and proxy vote fraud. More election fraud trials are pending around the country.

The Rowntree trust calls for new safeguards against voting fraud that have been introduced in Northern Ireland to be extended to the rest of the UK.

The Electoral Commission said that more reforms were needed. “We continue to urge the Government to replace the system of household registration with individual voter registration,” a spokesman said. “In many parts of the UK, structures for delivering elections are stretched to breaking point.”

The Ministry of Justice said that the Government had taken significant steps to protect the electoral process, including new penalties for vote fraud.

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