An investigation is under way into claims that thousands of General Election postal votes were never received by the Birmingham electors who applied for them.

City councillors have been inundated with complaints from constituents who registered to vote by post, completed the necessary paperwork, but were not sent a ballot paper.

Almost 60,000 postal votes were applied for but only 38,573 completed ballot papers were returned to the Council House - leaving more than 20,000 unaccounted for.

Members of an electoral matters scrutiny committee agreed yesterday to launch an urgent inquiry into the council's process for despatching postal votes. The contract to deliver ballot papers to homes across Birmingham was outsourced by the council to a private firm in Manchester. Inquiries will also focus on the role of Royal Mail in delivering voting papers.

Committee chairman Len Clark said he had been written to by a pensioner who applied for a postal vote because she was unwell and could not get to a polling station. The ballot paper never arrived.

Coun Clark (Con Quinton) added: "This, to me, lies at the heart of the process. This person was disenfranchised because of the way the system was administered and many others may have been similarly affected."

The committee will also consider ending the process whereby votes from all 11 Birmingham Parliamentary constituencies are counted at one venue - the National Indoor Arena. The possibility of returning to former arrangements - counting in each individual constituency - is under examination. Sutton Coldfield was counted separately this year as an experiment, leaving the ten remaining constituencies to be counted at the NIA.

However, traffic congestion in Birmingham city centre led to long delays in ballot boxes being delivered to the NIA and the count did not end until 4.30am.

Coun Paul Tilsley (Lib Dem Sheldon) said the thinking behind having one large count was that it would enable results to be declared more quickly and would give the " Birmingham brand" greater focus on television election programmes.

Unfortunately, most people had gone to bed by the time the results started to be declared in Birmingham this time," he added.

The committee will hear from witnesses including Sam Younger, chairman of the Electoral Commission.