Ballot spoiling concerns have spread to Twickenham with a voter reporting their paper was marked by an official.

The woman, who voted at Heatham House in Twickenham, said an official marked her number on both the register and her ballot paper.

"When casting my votes yesterday, as I showed my voting card to receive my ballot papers, a clerk recorded both my number on the voting register along with a number on my ballot paper," she said.

"When I queried this, asking how this could then be a secret' ballot, he told me that the information could only be accessed through a court order and it was unlikely the information would ever be used.

"I am shocked and appalled that there should be any way of checking how someone might have voted."

A London Elects spokesman said they had no confirmed incidents of ballot papers being marked in Richmond but would be investigating.

He said ballot papers that had been marked with a number but did not have any other way of identifying the voter would still be counted.

"If the voter's ID is discernable, it will not be counted," he said.

"There is a full investigation ongoing."

London Elects confirmed about 14 ballots had been spoiled by attendants in Lambeth.

He said London Elects found about five ballot officials across the capital who had acted incorrectly and they will not be hired again.