More than 3,000 missing Oxfordshire postal vote forms have been found by the Royal Mail in a sorting office - in Reading.

The mix-up could have left thousands of people across the Oxford West and Abingdon and Wantage constituencies unable to vote. Election officers said it could have affected the results, but believe people should now be able to vote.

On Monday, the returning officer for the Vale of White Horse District Council, Brian Smith, said 11,500 postal votes were issued across the two constituencies on Tuesday and Friday. But Royal Mail managers insisted they had only been given 8,190.

Today, it emerged that staff at Oxford's mail centre in Cowley sent the batch of postal votes to the sorting office in Reading instead of delivering them to voters.

Royal Mail spokesman Floyd Jebson said the missing papers were being delivered today, which would allow people to return them in time to be counted on Thursday night.

He said: "We have badly and unforgivably let down our customers. This should not have happened and a full investigation is under way.

"Gareth Bimson, who is our election co-ordinator in Oxfordshire, will be playing a major part in that investigation.

"A national conference of senior managers is also being held, to look at the way postal votes have been handled and the lessons we can learn. We apologise unreservedly to the Vale council. Any suspicion about the efficiency of their staff has been completely dispelled."

Mr Jebson said he would not be surprised if people now decided to take their postal votes to Abbey House in Abingdon and deliver them by hand.

Yesterday, hundreds of voters telephoned the Oxford Mail and the Vale council to complain that forms had still not arrived.

Mr Smith admitted only 1,500 completed forms had been returned.

He said: "I am very pleased that these votes have turned up. I just wish they had not gone missing on the first place.

"We will be checking our postboxes right up until 10pm on Thursday and if people want to bring in their postal votes they can do that right up until 10pm, here at Abbey House, or take them to any polling station in their own constituency.

"This has created a lot of heartache for people who thought they had lost their votes, and extra work for me and my staff."

The Conservatives only need a five per cent swing to regain the Oxford West and Abingdon seat, which Liberal Democrat Dr Evan Harris won with a majority of just over 6,000.

In 1997, Conservative Robert Jackson held the Wantage seat with a 6,039 majority. News of the mix-up angered the candidates fighting the Oxford West and Abingdon seat.