Ieuan Wyn Jones said help must be give to people facing redundancy
Plaid Cymru is calling for a £3bn stimulus package from the UK government to create and save 40,000 jobs in Wales between now and 2011.
In a discussion paper, The Road from Recession, Plaid also called for those earning over £100,000 to pay 50% tax.
Party leader Ieuan Wyn Jones hit out at what he said were Gordon Brown's planned £500m cuts to the Welsh budget.
It came the day after two firms in south Wales announced job losses, both blaming a slump in orders.
Unions and politicians have reacted anxiously after Novelis announced the closure of its aluminium sheet mill in Newport with 440 job losses.
Musashi Auto Parts is also planning to close its plant in Blackwood, Caerphilly with the loss of 124 jobs.
It follows the news on Tuesday that more than 300 jobs are to go with the closure of the Indesit washing machine factory in Denbighshire.
Mr Jones said Mr Brown's planned cuts showed a "worrying disregard" for the Welsh economy.
"The immediate priority must be to set the right conditions for economic recovery - in Wales that must be through effectively targeting support for businesses, through maintaining the skills base of our workforce and through providing the help we can to those facing redundancy," he said.
"What Wales needs from Westminster is a stimulus package to allow us to bring about that recovery as quickly as possible."
The union Unite's Welsh regional secretary Andy Richards said he feared Wales was facing "industrial devastation" following the recent announcements of job losses.
"This comes as a further nail in the coffin of manufacturing in Wales," he said.
"If ever the UK Government needed a wake up call to highlight the critical need for a proactive strategy to support UK industry and manufacturing jobs, then they need look no than Wales.
"Unite will do all in its power to assist the thousands of its members who are currently losing their jobs due to a crisis which was created by the greedy bankers.
"We have to repeat our warning to the government however that without immediate action, the current crisis will swiftly turn into a catastrophe from which there will be no hope of a recovery for the manufacturing sector."
Conservative South East Wales AM William Graham said the regularity of job loss announcements demonstrated how assembly government efforts to support industry in Wales appeared to be failing.
The two plants are 15 miles apart
"While I accept some of the circumstances which led to these announcements are beyond ministers' control in Cardiff there are measures they should be taking to stimulate the economy through business rate support and by providing access to credit," he said.
Rosemary Butler, Labour AM for Newport West said Novelis' decision was a "body blow" to the area and said she would work with her Welsh assembly colleague Irene James to ensure those who lost their jobs got the best possible redundancy packages and retraining.
"I'm very shocked that a company which was performing so well only six months ago is now closing so rapidly," she said.
Mr Jones's launch of the document called Recover, Reform, Renew: The Road From Recession on Thursday, was as Plaid Cymru leader, rather than as the deputy first minister and economic minister in the Labour-Plaid coalition.
This is because his party is approaching the European elections in June and a UK general election next year.
Although Plaid is in coalition with Labour in Cardiff Bay, it has to make clear its own separate identity to voters.