The clothing firm Burberry has announced a 22% increase of its revenue as it prepares to close its factory in the Rhondda.
Burberry products are known for their distinctive checked pattern
By the end of March, 300 jobs will be axed at Treorchy as the company says the plant is not commercially viable.
Burberry's total sales rose to £206m during the last three months of 2006 and the company opened two new stores.
But a union leader said workers at Treorchy would be "angry" and "frustrated" in light of the profits.
Mervyn Burnett a senior officer with the GMB union said the workers at the factory found it difficult to understand why the company had reached its decision to close the plant.
"Welsh workers in a British company with that level of profit have a right to assume their jobs are safe.
"It's no surprise the profitability of the company is up and the retail value of the company is up in lines with sales.
"We do not understand that a British company, making a British brand - doing so well - can then decide that the Treorchy factory becomes unviable."
According to the company - whose international expansion continues with new stores opening in California and Vienna - demand for luxury branded handbags and accessories helped lift Burberry's sales growth.
It has plans to open a further stores in Manchester, Seville and Prague during 2007.
Recently-appointed Burberry chief executive Angela Ahrendts said: "This outstanding quarter has been led by Burberry's strong retail performance.
"These results are a credit to the extended efforts of the team in executing our core strategies, specifically in innovating outwear, intensifying the luxury accessory offering and implementing operational enhancements."
Emma Thompson was the latest star to back Burberry factory workers
The factory at Treorchy has been producing clothes since 1939 but it was only taken over by Burberry in 1989.
After the closure was announced, it was reported that the polo shirts cost £11 to produce in the Treorchy factory compared to £4 in the Far East.
A high-profile campaign to keep the plant open would only intensify in light of the rising profits, according to Rhondda AM Leighton Andrews.
"Burberry's actions have damaged the 'Britishness' of its brand.
"'If Burberry wants to retain a reputation as a British company, it is high time its staff in Treorchy saw some fair play - or is that another of the 'British'' values Burberry is determined to reject?'"
However, a series of celebrity names, including actors Ioan Gruffudd - who advertises Burberry - Rhys Ifans and Emma Thompson have urged the company to keep the Rhondda plant open.
There have also been pickets at London Burberry stores.
The plant closure has also been criticised by Wales and Northern Ireland Secretary Peter Hain, who said such an "iconic British brand" should not be made abroad.