EURO MP Glenys Kinnock has written to bosses at Alcan in Rogerstone to register her fear over redundancy packages for axed staff.
The firm announced 310 job losses on Tuesday, and now Mrs Kinnock says she fears the level of packages with not be "appropriate".
But a spokeswoman for the company said: "Everything is subject to consultation at this stage. The redundancy packages offered will be enhanced over the statutory legal minimum and will be negotiated locally in line with local conditions."
Mrs Kinnock has been in correspondence with the management over the last year - campaigning for a fairer redundancy package for those made unemployed when Alcan closed down its foil mill 12 months ago.
Mrs Kinnock said: "This latest news a bitter blow for the workers at the Rogerstone plant and the surrounding area and it is happening just three weeks before Christmas and practically a year to the day of last year's job loss announcements."
Alcan has blamed the current economic climate for reducing its workforce around the world by between five and seven percent. However, at Rogerstone the workforce could be seeing 50% job losses.
Mrs Kinnock added: "Alcan has always been critical to the area and now we must ensure that an adequate package is put in place.
"My conversation with union representatives has convinced me that there is deep concern about the likelihood of a number of compulsory redundancies and that we might see, as we saw last year, a decision to offer Rogerstone a redundancy package which compares very badly with other plants affected by job losses."
The Conservative leader in the Assembly, Nick Bourne, has repeated his call for the immediate appointment of a full-time economic development minister. Rhodri Morgan currently fulfils the role alongside his duties as first minister in the temporary absence of Mike German.
Mr Bourne said: "It is now high time that Rhodri Morgan acknowledged that the interests of Wales far outweighs the flagging Lib-Lab coalition's political interests.
"Even Labour AMs have voiced their concern over Rhodri Morgan's blatant attempt to keep Mike German's seat warm. Manufacturing in Wales is in recess, the aerospace industry has already announced significant job losses and now we see Alcan also citing the events of September 11 as their reason for cutting jobs."
Mr Morgan has consistently rejected claims of recession, saying that the Welsh economy is in good health.
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