The majority of the world's biggest companies have not set targets to reduce emissions from business flights.

The Travel Smart Campaign, an international coalition of environmental charities, is working towards getting companies to reduce emissions from business travel to 50% of 2019 levels by 2025.

But it said only 50 companies out of the 322 surveyed have set targets to reduce business travel emissions.

This means 85% of the world's biggest companies have no targets set.

Of the companies who have targets, only four companies achieve the "gold standard" of promising to hit the 2025 target and fully report emissions from business flights.

The campaign argued that big gains are possible if companies took action.

"If 10% of companies - the biggest emitters of the ranking - set 50% reduction targets, this would go half the way towards achieving the global target of -50% in corporate air travel emissions by 2025."

Scientists agree that reducing aviation emissions is crucial to achieving the target of staying within 1.5°C of global warming.

Transport & Environment is a coalition member, and its Corporate Travel Manager Denise Auclair said, "Corporates are turning a blind eye to the harms done by flying for work. Most companies are taking little to no action on business flying, which renders any other travel targets meaningless in the context of tackling climate change."

The four companies that have signed up to hit 50% reduction by 2025 are Novo Nordisk (Pharmaceuticals, Denmark), Swiss Re (Finance, Switzerland), Fidelity International (Finance, United Kingdom) and ABN Amro (Finance, Netherlands).

The campaign also praised pharmaceutical companies AstraZeneca and Pfizer and consulting companies Boston Consulting Group and Deloitte who it said consider the full impact of flying in their reporting.

Travel & Environment said non-CO2 emissions from flying account for two thirds of the climate warming impact of flying.

It listed these as water vapour, sulphur dioxide and nitrous oxides and said companies should include these in their reporting.

The campaign argued that companies can and must cut emissions.

"The biggest emitters have a disproportionate role to play in reducing their corporate flying emissions. The means to achieve this are more accessible than ever before: rail travel when distances permit it and video conferencing to avoid long-haul flights," said Ms Auclair.