Crisis-ridden Jet Airways was on Tuesday forced to ground three of its Boeing 737 planes due to non-payment of lease rentals, leading to the cancellation of around 20 domestic flights, according to sources.

With three more planes taken out of operations, the number of aircraft on the ground due to non-payment of lease rentals by the carrier now stands at six in the last two days, the source added.

"Jet Airways has defaulted on aircraft lease rentals and it has been forced to ground three more narrow-body Boeing 737 planes," a source in the know of the development told PTI.

A response from the airline, which struggling with cash- crunch since the past many months, is awaited.

Due to the fresh grounding of the planes, the airline, which is negotiating with its partner Etihad for an additional cash infusion, has cancelled as many as 19 flights to/from Delhi, Chennai, Mumbai, Pune, Hyderabad, Port Blair and Bengaluru, the source added.