Former Labour MP Andrew Dismore may legally challenge the result of the poll in the Hendon constituency, which has one of the highest percentages of Jewish voters in the country.
Mr Dismore wrote to supporters asking them to provide him with evidence of disorganisation and proof they had been denied the chance to vote.
He lost the seat, which he had held for 13 years, to Matthew Offord, a former deputy leader of Barnet Council, by just 106 votes following a recount.
Mr Dismore wrote: “There were real problems at the polls here in Hendon due to the incompetence of Conservative Barnet Council. Many people did not receive their postal votes and so were denied their say. Others found queues so long they could not wait to vote or may even have been turned away.”
He claimed at least one polling station in a predominantly Labour ward was wrongly addressed on polling cards, meaning voters arrived at the wrong venue and could not vote.
He added: “If you were not able to vote for any of these reasons can you please let me know as a matter of urgency, as I am compiling a dossier which could possibly be used to challenge the result.”
Mr Dismore’s defeat left Hendon as the second most marginal seat in England.