Similar cases happen in domestic markets like Wu Mart and Merry Mart.

But a labor relationship actually exists between the supermarkets and these saleswomen, he said.

Take Sheng as an example. First, she was promoting Carrefour goods as the suppliers had sold their products to Carrefour. Second, Sheng's work like cleaning up, loading and unloading was directly assigned by Carrefour administrators. Third, Sheng was wearing a Carrefour uniform during work.

However, Sheng's demand was denied by a labor arbitration committee in Beijing, as she could not provide written material to prove a labor relationship between her and Carrefour.

Dong Baohua, a law professor of East China University of Politics and Law, said there is still a slim chance for Sheng to win the lawsuit.

"The disguised employment relationship is still an academic term," he said.

"And since Sheng has a clear labor relationship with Walch, which hired her, paid her and fired her, there is hardly a legal rule that would count Carrefour in."

"I did not slack off a bit after pregnancy," said Sheng, who has lost her job and is taking care of her 4-month-old baby in a village in Shandong province.

She dare not rest even if she was pregnant, as she knew the Carrefour watcher was monitoring and could ask Walch to fire her at any time.

Sheng said she often had to stand and work from 3 pm to 4-5 am when she was on night shift.

Sheng's husband now works as a taxi driver in Beijing, earning about 2,000 yuan a month.

The mother said it was a tough decision to have this child as they knew it is expensive to raise a child in Beijing, but she did not expect to lose her job for this.

Another 16 saleswomen hired by Beijing "Prince Milk" to promote the product in the Wu Mart, Merry Mart and Ikelong supermarkets who have similar experiences as Sheng also filed their cases to the labor arbitration authority yesterday.