British Prime Minister Theresa May called Tuesday for an early general election on June 8 in a surprise announcement as Britain prepares for delicate negotiations on leaving the European Union.

We need a general election and we need one now. We have at this moment a one-off chance to get this done... before the detailed talks begin, May said, despite previously denying that she would do so.

Speaking outside her Downing Street residence in London, May warned that division in Westminster will risk our ability to make a success of Brexit.

She said parliament would be asked to vote Wednesday to decide on whether or not to hold an election.

The dramatic announcement comes after months of tumult in British politics following the Brexit vote.

A round of opinion polls over the Easter weekend also showed her Conservative Party far ahead of the main opposition Labour Party.

The Conservatives polled at between 38 percent and 46 percent, with Labour at 23 percent to 29 percent, according to the polls by YouGov, ComRes and Opinium.

The poll lead had prompted many senior Conservatives to call for an election, particularly as May will need a strong parliamentary majority as she seeks to negotiate Britain's exit from the European Union.

The Conservatives currently have a working majority of just 17 from the last election in 2015 and some of their MPs have indicated they could vote against the government on key aspects of Brexit legislation.

British Opposition Labour Party leader Jeremy Corbyn walks along Westminster Bridge by the Houses of Parliament in central London, on March 23, 2017. (Photo by AFP)

EU leaders except May are set to hold a summit on April 29 where they will agree on the strategy for negotiating Britain's expected departure in 2019.

The negotiations themselves are not expected to start until May or June at the earliest. The European Commission has said it wants the exit talks to be concluded by October 2018 at the latest.

Britain's next election was due to have been held in 2020 -- a date enshrined in legislation according to which elections have to be held every five years in May.

But the law can be overruled if two-thirds of lawmakers in the British parliament vote in favor of early elections -- something that Labour leader Jeremy Corbyn has previously indicated he would do.

Corbyn, a veteran socialist with support on the left of the party, won the Labour leadership in September 2015 after the party's defeat in that year's election.