Millions of postal ballots are being sent to voters today.

The election papers are in clearly identifiable envelopes marked by two purple flashes, repeating the procedure criticised by a judge in Birmingham as being highly vulnerable to fraud.

In a separate development, police announced they were investigating electoral fraud allegations made against a Bradford councillor.

The claims relate to Jamshed Khan, a Conservative councillor in Bradford West, a Labour-held marginal, having 13 voters registered in his six-bedroom house. A further 12 people were found to be registered to vote at a derelict house that Land Registry records show he co-owned last year.

Meanwhile, the Department for Constitutional Affairs has published emergency warnings in 42 national, regional and ethnic minority newspapers, providing advice to householders on how to prevent their postal vote from being stolen.