Elections in Britain have been marred by reports from various constituencies where hundreds of voters were prevented from casting their votes because they turned up at polling booths near the closing time.
Long queues could be seen outside polling booths near the closing time. Election officers closed the doors of most such booths at the scheduled time (10pm), while people were allowed to cast their vote until 10.30 pm in some places.
The police had to intervene at booths in Manchester when people, upset at not being allowed to vote, turned restive.
There were also reports of some polling booths running out of ballot papers, raising serious questions on the Electoral Commission's preparation for the closely contested election.
An unprecedented statement from the Electoral Commission said: "The Electoral Commission will be undertaking a thorough review of what has happened. There should have been sufficient resources allocated".
In his Sheffield Hallam constituency, Liberal Democrat leader Nick Clegg went to offer his apologies to frustrated voters at a polling station in Ranmore after they queued for more than three hours.
Labour candidate Jack Scott said he was angry as people may have been denied the chance to cast their vote. Former Hillsborough MP Helen Jackson said it left any close results open to legal challenge.
In Londonderry, Northern Ireland, counting was suspended following a security alert after a hijacked car was abandoned in a car park.
The gymnasium where the count was taking place has been closed and the doors sealed, while army bomb disposal experts arrived at the scene.