Outside view of Flipkart office shot on October 01, 2015 in Bengaluru, India.

India's antitrust body has ordered an investigation into alleged competition law violations by Amazon.com Inc and Walmart's Flipkart, it said in an order on Monday.

The Competition Commission of India said that exclusive arrangements between mobile phone brands and e-commerce platforms, as well as allegations of e-commerce companies giving preferential treatment to certain sellers "merits an investigation".

The investigation is the latest setback for Amazon and Walmart's Flipkart, which Indian brick-and-mortar traders allege violate the country's foreign investment rules.

Both the companies deny those allegations.