Newspaper columnist Janet Street-Porter says there is a "campaign of hate" to try to save Rhondda's Burberry factory.
Burberry workers say they will take their campaign to the firm's AGM
She said the protests could damage the company globally with repercussions for the firm's remaining British workers.
But Welsh Secretary Peter Hain, who she also criticised, said he did not take seriously "the opinions of a so-called celebrity columnist in London".
He spoke after Charlotte Church became the latest celebrity opposing the closure of the 300-job Treorchy plant.
In her Independent on Sunday column, Ms Street-Porter said Burberry was one of many British firms which had chosen to move manufacturing outside the UK because it was cheaper.
"The economic reality of manufacturing in Gordon (Brown)'s highly-taxed, highly-regulated Britain means that British firms are moving more and more production overseas," she wrote.
She also criticised the campaigners for aiming their protests solely at Burberry, when several other companies had recently closed their operations in south Wales with the loss of hundreds of jobs.
Mr Hain was also accused by Ms Street-Porter of not doing enough to keep companies in south Wales.
Ms Street-Porter has had a varied career, including being a BBC executive and editor of The Independent on Sunday, where she is currently editor-at-large. She has also been president of The Ramblers' Association and was on ITV's I'm a Celebrity... Get Me Out Of Here!
"Burberry has 40% of its global workforce in the UK, with 600 people at factories in Rotherham and Castleford in Yorkshire making their iconic trenchcoat," she wrote.
"In spite of union claims, less than 10 per cent of Burberry production is in Asia, and it has increased its UK production staff.
"I am mystified as to why Burberry has been vilified for making a tough economic decision, while Tesco, Technicolor and Alcoa have not."
But Mr Hain responded by saying: "I don't really take seriously the opinions of a so-called celebrity columnist in London, especially one who is already so notorious for her alleged anti-Welsh comments. I doubt if she has ever even been to Treorchy."
Rhondda AM Leighton Andrews called the "campaign of hate" claim absurd. "We are simply standing up for the Burberry workers in Treorchy," he said.
In 2001, Ms Street-Porter - whose mother was Welsh - called the Welsh language "ugly and ludicrous" and claimed it was "only kept alive by committees inventing new words for modern inventions like the motor car and the television set". However, she later took part in a reality TV show to learn Welsh.
Meanwhile, workers at the Burberry factory in Treorchy say they plan to take their campaign to the company's annual general meeting in July.
As shareholders, they plan to question the company's decision.
Singer-turned-TV presenter Charlotte Church has joined fellow Welsh celebrities Tom Jones, Rhys Ifans, Ioan Gruffudd and Bryn Terfel in pledging support for the Burberry campaign.
She said: "If Burberry want to be seen as a British brand they should not be sending these jobs overseas."
In a letter published in the Sunday Telegraph, 179 of the 228 remaining workers also denied claims they are satisfied with the redundancy terms offered by Burberry.
Burberry has stressed that it has no plans to abandon the UK and offered Treorchy staff jobs in Yorkshire.
The company also said it would give the local community the factory and underwrite its assets, effectively valuing it at £1m. That offer, however, was rejected by the GMB union and politicians.