Voters were turned away from a polling station in Gosforth
A number of voters were turned away from a polling station on Tyneside as large queues formed outside others.
Newcastle City Council confirmed that about half a dozen people were too late to cast their votes in Gosforth.
In Jesmond and Heaton hundreds of people were queuing at 2200 BST although it is believed all were eventually able to gain entry.
The Electoral Commission has promised a "thorough review" into a similar incidents across the UK.
It said in a statement: "It is a cause for serious concern that many people who wanted to vote today were unable to do so when polls closed.
"Each returning officer is responsible for deciding numbers of polling stations in their constituency and the numbers of electors allocated to each polling station.
"By law, polls must close at 10pm and any voter issued with a ballot paper by 10pm should be allowed time to cast it, but no ballot paper should be issued after 10pm."
A spokesman for Newcastle City Council said: "In line with our understanding of election guidance, presiding officers took a pragmatic and common sense approach and allowed voters into the polling stations before locking the doors as required by law at 10pm.
"Voters inside the buildings at this point were allowed to vote. We consider that this decision was taken in the best interests of democracy.
"People arriving at polling stations after 10pm were turned away as it would have been illegal to admit them."
Voter turnout across the country was high, he added, and the late surge a "national phenomenon".
He said there was no evidence to suggest the way voting was handled had made any difference to the outcomes of elections in Newcastle.
The council also said that after every election it reviews polling station procedures to see if "any lessons can be learned for the future".