British Prime Minister Theresa May's call for a snap election was about taking advantage of the Labour Party's weakness in the polls, former UK Treasury minister Jim O'Neill told CNBC on Tuesday.
"It's pretty opportunistic politics," O'Neill said on "Squawk on the Street." "You look at the latest opinion polls, her party, the Conservative Party, is significantly ahead of the main opposition, the Labour Party.
European equities fell broadly after May's announcement Tuesday calling for a general election on June 8. Her announcement reversed a pledge she made after coming to power in the wake of the vote to pull Britain out of the European Union.
The prime minister said her decision had been made "recently and reluctantly," but she argued that the U.K. has a "one-off opportunity" to form a unified government while the EU decides its negotiating position on Brexit.
The announcement also sent the British pound for a loop. The currency rose more than 1 percent to $1.272 after briefly falling more than 1 percent.
"We need a general election and we need one now," May said outside 10 Downing Street.
O'Neill, a Conservative Party member and a former Goldman Sachs asset management chairman, said the prime minster's choice was risky considering she had promised no such election would happen.
"But she's looking at the weakness of the Labour Party and thinking it is a low-risk strategy," he said.
—CNBC's Karen Gilchrist and Fred Imbert contributed to this report.