The airline, which suspended its international flight programme last week, has extended this through Thursday this week (18 April).
This includes its Manchester-Mumbai service, which was pulled in March, as well as its Heathrow-Mumbai and Heathrow-Delhi routes.
It is understood the airline has been left with just seven operational aircraft, which have been deployed on Indian domestic services.
The airline’s debts are believed to have stretched to more than £900 million, the BBC reports. Chief executive Vinay Dube told staff “interim funding hadn’t been forthcoming”.
It has also been reported Jet has transferred its slots at Heathrow to Etihad, which has a 24% stake in the airline.
Currently, all flights advertised for sale on Jet Airways’ website are operated by the Middle Eastern carrier.
The airline’s board will meet again on Tuesday (16 April) to try to find a way forward. The Times of India reports a temporary shutdown of the entire airline is among the options under discussion.
Jet Airways chairman Naresh Goyal stood down last month allowing a consortium of investors led by State Bank of India to pursue fresh funding.