Do you have observers to spare, Mr M?

It's the nightmare scenario: Labour wins the general election with a single-figure majority but challenges are mounted in constituencies up and down the country, alleging electoral fraud. The police open investigations and even if they eventually decide there has been no wrongdoing, Tony Blair is for a time the head of a government whose legitimacy is in doubt. Highly unlikely, you may say, given that this is the UK, not Zimbabwe, but consider this. Following last year's local elections, there have been claims of electoral fraud in more than half a dozen British towns and cities, some of which are still under investigation almost a year later.

The reason is simple. Faced with falling turnouts, the Government has made it easier to vote by allowing an unprecedented number of people to use postal ballots. It sounds good in practice, and the percentage of people voting in local elections has risen as a result. So, though, have allegations of fraud. To date, few of them have been tested in court, and the fact that some involve wards with high numbers of Asian voters means that they are very sensitive.

Some observers claim the allegations are racist - the newspaper that has compiled the most detailed dossier so far is, I'm afraid, the Daily Mail - while others argue that the extension of postal voting has provided an opportunity for corrupt electoral practices from abroad to be imported into the UK. Two cases last week shed some light on the allegations: on Friday, a former Labour councillor in Blackburn, the constituency represented by the Foreign Secretary, Jack Straw, was jailed for three years and seven months after admitting conspiracy to defraud the returning officer in the 2002 local elections. Muhammed Hussain's supporters knocked on doors and asked voters to hand over blank postal votes, telling them: "Don't worry, we'll take care of them." Four days earlier, another judge found six Labour councillors guilty of electoral fraud. Richard Mawrey QC, sitting as an electoral commissioner in Birmingham, said he had heard evidence of "overwhelming fraud" in two wards in last year's city council elections. He identified 15 types of fraud, including wholesale theft of ballot papers and the discovery of a "vote-forging factory".

Anxieties about postal voting are not confined to the political right. Ann Cryer, the admirable Labour MP for Keighley, suggested last year that whole communities had been pressured into voting one way after an all-postal election in Yorkshire and Humberside. "The Asian community tend to stick together," she said. 'If one of their elders comes to the door and asks them to do something, they by and large do it." Another Yorkshire MP, Marsha Singh, has also suggested there was widespread fraud.

The Electoral Reform Society does not believe that the outcome of the general election is likely to be "seriously affected" by fraud. Judge Mawrey is less sanguine, declaring there are "no systems to deal realistically with fraud and there never have been". He described checks against corruption as "hopelessly insecure" and accused the Government of being in denial about the risks to democracy.

I am instinctively opposed to postal voting for those physically capable of making it to the polling station, and not just because of the danger of fraud. Rituals are important - look at the millions who converged on Rome last week for the funeral of John Paul II - and the act of going to a polling station is a secular ritual which confirms the fact that we live in a participatory democracy. If we expect people to vote in person in Iraq, where they have to defy suicide bombers, I don't think it's too much to ask adults in this country to walk to a nearby school or community centre.

Instead of turning voting into a private act, as insignificant as applying for a credit card, the Government should make election days a public holiday in which we express our commitment to the democratic process. Instead, it has pressed ahead with a flawed voting system that has already undermined confidence in the results of last year's local elections. If I were Robert Mugabe, I'd be on the phone to Tony Blair, offering to send election observers.