A senior UK Labour MP says the party will make "appropriate decisions" about Jeremy Corbyn's leadership if the election results are as bad as exit polls and initial counting suggests.

Key points: Labour is on track for its worst result since 1935

Labour is on track for its worst result since 1935 Shadow chancellor John McDonnell says Jeremy Corbyn's fate will be decided tomorrow

Shadow chancellor John McDonnell says Jeremy Corbyn's fate will be decided tomorrow Voter antipathy towards Corbyn hurt the party, MPs say

Boris Johnson's Conservative Party is predicted to win the UK election with its largest majority in decades, according to a BBC/ITV/Sky exit poll released immediately after voting ended.

Mr Corbyn's Labour Party is on track to lose more than 70 seats in its worst result since before World War II.

Labour's shadow chancellor John McDonnell said Mr Corbyn's future, as well as his own, would be decided once all the results were in.

"We'll see the results in the morning and then decisions will be made, I'm sure then," he told the BBC.

"The appropriate decisions will be made," he said when asked if his career — and that of Mr Corbyn — was over.

But Mr Corbyn already indicated he would be stepping down as Labour leader.

He said he intended to remain in Parliament and would remain leader of the party until a replacement was appointed.

"I will discuss with our party to ensure there is a process now of reflection, on this result, and on the policies that the party will take going forward," Mr Corbyn said after retaining his seat of Islington North.

"And I will lead the party during that period to ensure that discussion takes place and we move on into the future."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 59 seconds 1 m 59 s Labour leader Jeremy Corbyn says he will not lead the party to any future elections.

Mr Corbyn said Brexit had overshadowed his social justice policies during the election campaign.

"Brexit has so polarised and divided debate in this country, it's overridden so much of a normal political debate, and I recognise that has contributed to the result that the Labour Party has received this evening, all across this country," he said.

"The issues of social justice and the issues of needs of people will not go away."

Several Labour candidates have already publicly blamed Mr Corbyn's leadership for the party's electoral defeat.

Phil Wilson ran in the constituency of Sedgefield — which has been held by Labour since 1935.

On Twitter he said Mr Corbyn's leadership "went down like a lead balloon on the doorstep."

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Labour MP Margaret Hodge slammed Mr McDonnell for suggesting that the party lost support over Brexit, instead calling the result "an utter failure of Corbyn [and] Corbynism."

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ABC chief election analyst Antony Green said the results could be a "a disaster for Jeremy Corbyn and the Labour Party."

"For Prime Minister [Boris] Johnson, it provides him with the numbers to 'Get Brexit Done', and a big enough majority that he can choose to sideline some of the more hard-line Brexiteers," he said.

Labour's international development spokesman Barry Gardiner said the exit poll was a "devastating blow" for his party.

Labour candidate Gareth Snell said he expected to lose his seat in Stoke-on-Trent — a city once regarded as a Labour stronghold.

When asked if it was time for Mr Corbyn to go, Mr Snell replied: "Yes".

Former Labour home secretary Alan Johnson savaged Mr Corbyn's leadership and said he was angry the party had "persevered" with him.

"Everyone knew Corbyn couldn't lead the working class out of a paper bag," he said.

"We knew he was incapable of leading, we knew he was worse than useless at all the qualities you need to lead a political party."

The most unpopular opposition leader since polling began

Prime Minister Boris Johnson is on track to win a big majority in the UK Parliament. ( Reuters: Toby Melville )

An opinion poll carried out earlier this year found Mr Corbyn was the most unpopular opposition leader since polling began in the UK 45 years ago.

The poll, conducted for London's Evening Standard newspaper, which is edited by former Conservative chancellor George Osborne, gave Mr Corbyn a net satisfaction rating of -60.

Ipsos Mori found that 16 per cent of voters were satisfied with Mr Corbyn's performance, while 76 per cent said they were dissatisfied.

Former Labour leader Michael Foot had an approval score of -56 in 1982 — a year before he lost in a landslide to Prime Minister Margaret Thatcher.

Reuters/AP