Theresa May is to make a statement in Downing Street at 11.15am after Cabinet.
"It's a political move to establish opposition in terms of her opposition to the Labour Party", he said.
British and European Union negotiators said the election would not affect the timetable for Brexit negotiations. European Union leaders will meet in Brussels on April 29th to agree negotiating guidelines but substantive negotiations are not expected to begin for another month.
May took office in July after predecessor David Cameron stepped down following his failed attempt to get voters to back remaining within the EU. Since then she had repeatedly ruled out calling an early election to get her own mandate.
During her walks in Snowdonia she discussed the dilemma with her husband Philip, and between them they came to the conclusion that an election was not only in the country's interests, but overrode any sniping Mrs May might have to endure about a U-turn.
May said that if there is not an election soon, "the negotiations with the European Union will reach their most hard stage in the run-up to the next scheduled election".
"Division in Westminster will risk our ability to make a success of Brexit and it will cause damaging uncertainty and instability to the country", she said. "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", on leaving the EU, May said. Stop-loss driven buying emerged in layers beginning above 1.2650 and extending beyond 1.2800, said traders in London, Toronto and Europe familiar with the transactions who asked not to be identified because they are not authorized to speak publicly.
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 lawmakers vote for it.
That is highly likely to happen on Wednesday.
Despite Labour's poor showing in the polls, the party says it has financial reserves, that it is prepared for an election, and that it will present a viable "alternative" government to the Conservatives.
The Liberal Democrats have promised to bludgeon the Conservatives with the specter of a "hard Brexit", in which Britain would leave the EU's single market and customs union without a mitigating trade agreement. He said Labour would fight the election promising a fairer society and economy, and "a Brexit that works for all".
French opinion polls show that far-right leader Marine Le Pen and centrist Emmanuel Macron qualifying next Sunday for the May 7 run-off, but the gap with conservative Francois Fillon and far-leftist Jean-Luc Melenchon has been tightening.
Sturgeon said Tuesday that May was seeking "to crush the voices of people who disagree with her".
And although the Scottish Nationalists can hardly do better than the huge victory they scored at the last general election when they went from six to 56 electoral seats, if they manage to hold on to most of their seats, that would be interpreted as a rebuff to the British government and may well precipitate fresh demands for Scottish independence, precisely what Mrs May is keen to avoid.
The dollar edged up 0.1 percent to 108.57 yen JPY=, while the euro was steady on the day at $1.0732 EUR= after riding sterling's coattails to three-week highs overnight.