Britain officially launches general election campaign

Britain's opposition Labour Party leader Ed Miliband attends the presentation of their business manifesto in central London March 30, 2015. Campaigning in Britain's closest national election in decades started on Monday after the Prime Minister David Cameron meet Queen Elizabeth following parliament's dissolution, teeing up an unusually fraught battle to govern the $2.8 trillion economy. [Photo/Agencies]

"Ed Miliband pays lip service to working people while planning to hike taxes and increase debt. After five years of effort and sacrifice, Britain is on the right track. This election is about moving forward - and as Prime Minister here at Number 10 that is what I will deliver," the prime minister told the press.

Miliband, meanwhile, outlined the Labor Party's business manifesto in London on Monday. He attacked Cameron's promised referendum on Britain's European Union (EU) membership as a "clear and present danger" to the economy.

He said that the referendum would lead to two years of "uncertainty" and "wasted opportunities."

"It threatens to shut UK businesses out of a market that gives them access to the world's largest trading bloc. It's simply the wrong direction for our country," he warned.

"If you care about strong foundations, if you care about long-term stability, if you care about prosperity, then Britain must be a committed member of a reformed European Union," he told voters.

"Not threatening to leave. Not locked out of the room. The job of the next prime minister is to open new markets for business, not close them off," the Labor Party leader affirmed.

Cameron has pledged to hold an "in or out" referendum on whether Britain should withdraw from the EU by 2017, if his Conservative Party wins the 2015 general election.

Britain is to hold its next general election on May 7. A party needs to win at least 326 of all 650 seats in the House of Commons,

the parliament's lower house, to form a majority government.

Recent opinion polls show that the Conservatives and the Labor Party have been neck and neck in support. The Scottish National Party (SNP) and the Eurosceptic UK Independence Party (UKIP) are also expected to win more seats in the Parliament, making the general election the most unpredictable one in a generation.