"This FDI (foreign direct investment) is not in favour of the consumer, farmer, trader, manufacturer and the country. That's why we are opposing it and will continue to oppose it till our last breath," Jaitley said as he addressed a rally held at Ramlila Ground here by the Confederation of All India Traders (CAIT).
"We stand united with the traders and the people of this country," he added.
The senior Bharatiya Janata Party (BJP) leader argued that under FDI, 60-70 percent of the business will go into the hands of just two or three companies which will be harmful for the farmers.
"The farmers would be left with no choice but to sell their produce to them. When the number of sellers decrease, how will it benefit the farmers?" asked Jaitley.
Other senior leaders who attended the rally were BJP chief Rajnath Singh, prominent party leader Murli Manohar Joshi, Delhi BJP chief Vijay Goel and Communist Party of India (CPI) leader A.B. Bardhan.
Several markets in the capital remained closed as traders down shutters in protest.
According to Narender Madan, Delhi unit president markets like Kamla Nagar, Chawri Bazar, Kashmere Gate, Tilak Nagar remained closed Thursday.