MUMBAI: The worldwide cab hailing firm Uber has tied up with Axis Bank and HDFC Bank for UPI (Unified Payments Interface)-based payments. The announcement is expected in a couple of days.Apart from payments via credit/debit cards, cash and Paytm , this will be yet another payment option available to customers.Uber’s chief competitor in the Indian industry, Ola had incorporated UPI this year in April.According to rough estimates, more than half of Uber cab drivers still get paid by users in cash. Industry estimates suggest that while Uber has 2.4 lakh drivers registered with them, Ola has an estimated 6.5 lakh drivers working for it.NPCI is also ready to roll out UPI partnerships with multiple banks for international players such as WhatsApp and Google soon. Amazon is also talking about the roll out of UPI with handful of banks.UPI is a payment system launched by NPCI which facilitates instant fund transfer between two bank accounts on the mobile platform.Transaction volumes of UPI rose by over 10% to 11.63 million in July as per NPCI data. UPI volumes during the last three months were 9.36 million, 10.35 million and 11.63 million while the value stood at Rs 2,797.07 crore, Rs 3,098.36 crore and Rs 3,411.35 crore in May, June and July 2017, respectively.UPI was launched in August 2016 with 21 banks and it is currently being offered by 52 banks. Out of the total UPI transaction volume, over 22% are merchant-based.