Also referring to itself as the Department for Personal Insolvency Review and Assessment, the IVA Review Board is licensed under the Consumer Credit Act.

In December the IVA Review Board's parent company, INTL Marketing, had its Consumer Credit Licence revoked by the OFT, but the firm subsequently launched an appeal. While this appeal is pending, the company's licence remains active.

Industry experts have warned that such letters could lead to debtors defaulting on their IVAs, and thus becoming exposed to other debt recovery techniques. In the vast majority of cases, if a debtor falls more than three months into arrears, the IVA will be terminated automatically.

These letters carry many similarities to ones issued by the IVA Council in 2008, which gained notoriety for imitating the Insolvency Service website and contacting people in IVAs claiming they had been mis-sold the arrangement.

It is not yet known if there is any connection between the IVA Review Board and the IVA Council.

A spokesperson at the Insolvency Service said: "If people in IVAs receive any unsolicited communication suggesting that they stop making payments, they should discuss this in the first instance with the supervisor of their IVA."