Mr Brown said failure to act now would mean a deeper and longer recession
Gordon Brown has promised to help 500,000 people into work or training, as the government attempts to stop unemployment increasing further.
The prime minister said employers would be given up to £2,500 for every person they trained who had been unemployed for more than six months.
Hosting a jobs summit, he promised that communities would not be "written off".
With 1.8 million people out of work, the Conservatives say the government's job package "does not go far enough".
'Not on my watch'
Mr Brown's announcement came as administrators for the ceramics firm Wedgwood confirmed 367 staff are to be made redundant and digger manufacturer JCB announced a further 684 job losses on top of 1,000 redundancies made last year.
More than 400 jobs are also under threat at Findus frozen food firm Newcastle Productions, which has also gone into administration, and another 875 at distribution company Wincanton, after it confirmed two of its depots may close in the spring.
Kent-based retailer Land of Leather also announced it was going into administration but would continue to trade while a buyer was sought.
But, on a brighter note, supermarket chain Morrisons unveiled plans to take on 5,000 extra staff for its store expansion programme.
In a speech at the Science Museum in London, Mr Brown set out plans to prepare Britain for growth in sectors such as environmental technology, advanced manufacturing, healthcare and education.
He said: "Failure to act now and to do so in coordination with our international partners would mean a deeper and longer global recession.
There are fears that three million people could be unemployed by 2010
"It would mean temporary rises in unemployment becoming permanent. It would mean as in the past whole communities written off, and that would mean lasting damage to our economy and a bigger bill to pay in the future. And this will not happen on my watch."
Mr Brown said: "We cannot always prevent people losing their jobs but we can help people finding their next jobs."
He told the audience that people unemployed for three months or more would also get help, including "extensive" job interview training, and would have to sign on weekly for benefit payments.
Work and Pensions Secretary James Purnell said of the £500m scheme to help people who have been out of work for more than six months: "What we have learned from previous recessions is we need to make sure people don't feel out of touch with the labour market...
"We don't want to waste a generation of people, as has happened in the past."
Since being made redundant it's become obvious that the jobs aren't out there. And what jobs there are, an awful lot of people are applying for them
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