Prime Minister Theresa May is due to visit Queen Elizabeth II to mark the dissolution of Parliament – the official start of Britain’s election campaign.
Ms May said she needed to strengthen her hand in divorce talks with the European Union by shoring up support for her Brexit plan.
Standing outside 10 Downing Street, Ms May said she would ask the House of Commons on Wednesday to back her call for an election, three years before the next scheduled date in May 2020.
She said that since Britons voted to leave the EU in June the country had come together, but politicians had not, and those divisions “risk [the UK’s] ability to make a success of Brexit”.
At present, Ms May’s governing Conservatives have 330 seats in the 650-seat House of Commons.
“Our opponents believe that because the Government’s majority is so small, our resolve will weaken and that they can force us to change course” she said.
“They are wrong. They underestimate our determination to get the job done and I am not prepared to let them endanger the security of millions of working people across the country.”
Under Britain’s Fixed-Term Parliaments Act, elections are held every five years, but the prime minister can call a snap election if two-thirds of MPs vote for it.
A spokesperson for Ms May said the Prime Minister spoke to Queen Elizabeth II by phone on Monday, and that an early election would not affect the timetable for Brexit.
It was Hitchcock, who directed Brexit: first an earthquake and the tension rises.
— Donald Tusk (@donaldtusk) April 18, 2017
No change to Brexit timetable: EU
Spokesman for European Council President Donald Tusk, Preben Aamann, said the EU would stick to the timetable for preparing to launch Brexit negotiations, despite the snap election.
Mr Tusk said on Twitter he had a “good” telephone conversation with Ms May after she called for the election.
In a separate tweet, the former Polish Prime Minister likened the surprising twist in the Brexit saga to a movie plot by the British master of suspense Alfred Hitchcock.
“It was Hitchcock who directed Brexit: first an earthquake and the tension rises.”
Mr Tusk was referring to a comment attributed to the late filmmaker that a good film “should start with an earthquake and be followed by rising tension”.
Sturgeon says May’s aiming for a ‘hard Brexit’
The leader of the main opposition Labour Party, Jeremy Corbyn, said he welcomed Ms May’s decision “to give the British people the chance to vote for a government that will put the interests of the majority first”.
“We look forward to showing how Labour will stand up for the people of Britain,” he said.
However Scotland’s First Minister Nicola Sturgeon, whose party seeks independence from the United Kingdom and opposes leaving the EU, said Ms May was trying to force Britain into a “hard Brexit”.
“The [Conservatives] see a chance to move the UK to the right, force through a hard Brexit and impose deeper [public spending] cuts,” Ms Sturgeon said.
“Let’s stand up for Scotland.”
Ms May took office in July after her predecessor David Cameron stepped down following his failed attempt to get voters to back remaining in the EU.
Since then she has ruled out calling an early election to get her own mandate, but now says she has since “reluctantly” changed her mind.
“It was with reluctance that I decided the country needs this election, but it is with strong conviction that I say it is necessary to secure the strong and stable leadership the country needs to see us through Brexit and beyond,” she said.
Polls gave Ms May’s Conservatives a double-digit lead on Labour, which is divided under left-wing leader Mr Corbyn.
British shares headed for their worst day’s drop since the aftermath of the Brexit referendum last June following Ms May’s announcement.
The FTSE 100 dropped 1.6 per cent to its lowest in more than seven weeks as the sterling inched higher, further weighing on the index’s stocks, most of which get earnings in foreign currencies.