Published Monday, 30 September 2013
He said the region could face a cut to its block grant if new policies outlined by the government are not taken up by the Executive.
Chancellor George Osborne unveiled a tough new scheme on Monday, which would see the long-term unemployed have to do community work placements, visit a job centre every day or take part in compulsory training to qualify for benefits.
The reforms would mean changes for thousands of people in the region.
Speaking to UTV, Mr Cameron said: "We hope that we can reach that agreement.
"Obviously in the end the amount of money is limited so if welfare is not reformed in Northern Ireland the Executive has to make decisions about how that money is spent.
"The block grant, in the end, does depend on the individual constituents, and if one of the individual constituents welfare is left unreformed then that will have an effect on NI."
Mr Cameron's officials have written to the Executive to point out that there could be a loss of around £60m to the block grant released by the Treasury if the plans do not go ahead.
"I hope they can see the sense in reform," Mr Cameron continued.
"Remember, reform is not simply about cutting the bills, it is about helping the long-term unemployed into work and that is a very positive story."
It is significant that they are starting to step up the pressure.
UTV's Political Editor Ken Reid
Local politicians have raised concerns about Mr Osborne's proposals.
East Antrim MP Sammy Wilson said: "Whilst I believe that it is imperative that all who are able to work should do so, it is important that measures to get people into work are practical and workable.
"I am however concerned about the proposal to force long term unemployed to report to the social security office on a daily basis. Apart from the fact that this appears to be some form of punishment for not having a job, it will be costly to both the state and the individual," the DUP MP said.
"Social security offices would be inundated with people signing on daily. Let us make it clear that not working when able should not become a life style choice, but make sure the policies don't have consequences which incur unnecessary expenditure or hardship."
SDLP Foyle MP Mark Durkan said: "These plans are not about improving the position of those without work or the condition of the economy.
"They are about positioning George Osborne and the conditioning of the start of a divisive debate with a partisan electoral motive."
Sinn Féin MLA Mickey Brady said the proposed reforms would "punish" the unemployed who cannot get work due to ill health, lack of skills and mental health issues.
"The quickest route to returning people to work is creating employment, and promoting skills through training schemes, not by forcing people into working for what can amount to £56 a week," he said.
"Essentially the British Chancellor is promoting a workhouse mentality," said the Newry and Armagh MLA, adding he "would be better spending his time offering people the correct support and job opportunities that would help them find meaningful and long term, secure employment."
Mr Cameron is due to visit Northern Ireland next month.
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