LONDON- Global airline industry body IATA warned that the outlook for airlines had weakened since its December forecasts, and due to tightening travel restrictions it now expected the sector to still be bleeding cash by the fourth quarter of this year.

IATA raised its forecast for total airline cash burn for 2021 to between $75 billion and $95 billion, up from the $48 billion it had forecast in December.

While many countries have started rolling out vaccines to tackle the novel coronavirus, the emergence of more infectious variants in countries such as Britain, Brazil and South Africa has forced many governments to ban all but essential travel.

This summer is make-or-break for many airlines and holiday companies which are struggling to survive with close to a year of almost no revenue due to pandemic restrictions. Without it many will need extra funds after burning through cash reserves.

Britain's Heathrow Airport said on Wednesday it had plunged to a 2 billion pound loss in 2020 and that digital health checks were now vital to building any kind of recovery in international travel. 

IATA also said on Wednesday it planned to launch a COVID-19 travel pass at the end of March, bringing into use a digital system for test results and vaccine certificates which will help facilitate travel.

(Reporting by Sarah Young; Editing by Kate Holton and James Davey) ((sarah.young@thomsonreuters.com; +44 20 7542 1109; Reuters Messaging: sarah.young.thomsonreuters@reuters.net))