Tony Blair and Gordon Brown have pledged to give UK industry a boost if they secure a third term, hailing Labour as the "party of enterprise".
Labour want to make economy the campaign's central issue
Outlining their business manifesto, they promised to set up a manufacturing skills academy and increase the number of apprenticeships to 300,000.
The prime minister said he wanted to make the economy the central issue of the election campaign.
But the rival parties are turning up the heat on Labour over the Iraq war.
As Number 10 published the attorney general's full advice about the legality of the Iraq war, Tory leader Michael Howard asked how Mr Blair could be trusted "ever again".
Liberal Democrat leader Charles Kennedy says he wants the prime minister to give a full statement on the issue.
The advice was published after part of it was leaked to the media on Wednesday night.
Tony Blair defended his actions, and referred to the leaked advice as a "damp squib" not a "smoking gun".
The three party leaders are set to appear - separately - on a special edition of BBC One's Question Time.
Mr Blair told an audience of business leaders that Britain had never worked so productively, created so much wealth or so many jobs.
But he stressed that countries such as India and China were now competing with the UK on skills as well as costs.
"Between them, these two countries produce 125,000 computer science graduates every year, more than twice the whole of the EU.
"British business can rise to these challenges, competing successfully in an ever more competitive global economy."
Mr Blair said it was essential that economic stability and a competitive tax regime was maintained, and the regulatory burden reduced.
"We fought very hard to establish our reputation as the party of entrepreneurship - it's not a reputation we want to lose."
Mr Brown said Labour would increase the number of apprenticeships by 75,000 in the next Parliament, raising the total to 300,000 by 2008 and a new goal of 330,000 by 2010.
British Gas will confirm its commitment to 500 more apprenticeships this year, with a focus on women recruits - Mr Brown is visiting its training academy in London later on Thursday.
"We will make the historic commitment that every young person will have, for the first time, the opportunity of education or training to the age of 18 and by 2006 offer enterprise training in every skill," he said.
He said Labour would encourage deregulation, with one million fewer inspections of business.
He also proposed reforming the local authority regulatory regime to further reduce business inspections.
Mr Brown said science investment would rise from £1.3bn in 1997 to £3.4bn a year by 2007.
The Tories would cut investment in training, science and infrastructure, "investment that is vital to meet the future needs of our economy", he said.
Tony Woodley, general secretary of the Transport and General Workers Union, welcomed the announcement of a skills academy, saying it showed Labour's commitment to manufacturing and developing workers' skills throughout their careers.
The Liberal Democrats abandoned their planned announcement of proposals to tackle hospital superbug MRSA to concentrate on Iraq.
A spokesman said the party would instead outline their health proposals at the weekend.
The Tories' morning press conference focused briefly on education before turning to the issue of Iraq.
Mr Howard said his party would give teachers support to enforce discipline in schools, protection from abuse at work, and would allow them to run their classrooms.
They would also give head teachers control over admissions and expulsions and insist on parental cooperation.
The three main party leaders will appear on BBC One's Question Time at 2030 BST on Thursday.