David Cameron promises 'relentless' push for growth
David Cameron has promised a "forensic, relentless approach" to ensuring the UK's future economic growth.
The government would offer help to ensure new companies can prosper, the prime minister told the CBI conference.
He also hinted at making the cap on skilled non-EU migrants able to work in the UK more flexible amid concerns from business it will hamper the recovery.
Labour leader Ed Miliband said the coalition government lacked a credible plan for boosting growth.
The government argues that, while 490,000 public sector positions are forecast to close as public spending is cut, new jobs will be created by the private sector.
Mr Cameron said he wanted to help new companies break into existing markets and pledged funding for a network of centres to make research more commercial and to help spur job creation.
On immigration, he stressed the need for it to be brought down to a "manageable level" but told business leaders that "we will not impede you from attracting the best talent from around the world".
The Conservatives say they will fulfill a manifesto pledge by introducing a permanent cap on the number of people from outside the EU able to take up work in the UK from next April.
However, a temporary limit of 24,100 which came into force this summer - to apply until April - has already caused anger with banks and other multinational businesses arguing that it is restricting their ability to recruit the best candidates at a time of need.
Business Secretary Vince Cable has repeatedly called for flexibility in how the cap is administered - seen as calling for it to be set as high as possible.
But No 10 said Mr Cameron's remarks did not signify there was a "rethink" on the permanent cap - currently the subject of consultation.
"We will be looking obviously at the level of that cap and at the way in which it operates and making sure that works in a way that allows business to bring the people that they need into the UK," a No 10 spokesman said.
On the wider issue of how to boost growth and job creation in the private sector, Mr Cameron said his commitment to sharply reduce borrowing over the next four years would provide a stable climate for business to invest.
"This is an incredible opportunity for Britain, for new start-ups to flourish, for innovations to drive growth and create jobs," he said.
"To build that new dynamism in our economy, to create the growth, jobs and opportunities Britain needs, we've got to back the big businesses of tomorrow, not just the big businesses of today."
Although the economy picked up over the spring and early summer, some economists expect figures out on Tuesday to show a slowdown during the third quarter.
The prime minister said the UK had sometimes been "complacent about our competitive advantages", whereas the coalition wanted a change in attitude.
He told business leaders a "forensic, relentless focus on growth is what you will get from the government".
Unveiling what he said was the UK's "first-ever national infrastructure plan", Mr Cameron said countries such as China had been investing massively in new roads and rail links while the UK had "stood still".
"Even in this very constrained time, we will invest over £30bn in transport projects over the next four years," the prime minister said, adding that he wanted government action to help "unlock" £200bn in total public and private sector investment in transport, energy, telecommunications and other critical sectors.
CBI director general Richard Lambert said Mr Cameron showed an understanding "that only business will create growth".
"There was a welcome emphasis on the need to re-boot the country's infrastructure, with a coherent vision of what needs to be done over the next five years to secure economic growth," he said.
'Hostage to fortune'
Mr Miliband, in his first major speech on business since becoming opposition leader, said Mr Cameron had failed to learn lessons from the financial crisis and the government could become a "hostage to fortune".
He said: "As much as I am worried about the job cuts and pace of retrenchment in the government's deficit reduction plan, I am equally worried about its failure to provide any sort of wider economic policy.
"Without profound change in the way we manage our economy, we are at risk of - at best - sleepwalking back to an economy riddled with the same risks as we saw before the recession hit."
The TUC said business investment had been to low and biased towards property and finance.
"Some in government seem to think that public sector cuts will automatically spur private sector growth, but with cuts hitting both public purchasing and consumer confidence, it is more likely that the cuts will take down important parts of the private sector too," TUC general secretary Brendan Barber said.