Hundreds of people in west London have been prevented from voting in the general election by a clerical error.
Hounslow Council said several hundred people could be affected after names were deleted from the electoral register in two constituencies.
A spokesman added that the full extent of the problem would not be known until an audit had been carried out.
The mistake was uncovered last Thursday but under election guidelines it was too late to resolve it before polling.
The affected constituencies are Feltham and Heston, and Brentford and Isleworth.
A council spokesman said: "We do not know how many voters are affected but it could be several hundred.
"The two constituencies together have in excess of 160,000 electors on the register."
The spokesman added it had apologised to the voters involved but staff at polling stations had been briefed to explain the situation to the affected individuals.