Crisis-hit airlines said Tuesday that a plan to cap the growth of the industry's emissions by 2020 was ambitious and costly but agreed on the urgency of fighting climate change.

"It's a very ambitious target, I keep my fingers crossed," Qatar Airways chief executive Akbar Al Baker told fellow delegates to the annual meeting of the International Air Transport Association (IATA).

"I'm not against it but it has to be level playing field, we are affected by the CO2 emission as well because we are living on the same planet too, but it's unfair for us to have certain rules for a certain sector," he said.

"The whole exercise will make air travel so expensive and we will have to pass the expenditures to passengers," he said, calling the 2020 deadline a "hot potato" handed to airlines.

The fuel-guzzling industry, under attack from environmentalists for its contribution to global warming, faces estimated losses of 20 billion dollars in 2008 and 2009.

Despite the global financial crisis, IATA declared on Monday that it was committing itself to the 2020 deadline through improved technology, more efficient planes, widespread use of biofuels and other measures.

"After this date, aviation's emissions will not grow even as demand increases. Airlines are the first global industry to make such a bold commitment," IATA chief Giovanni Bisignani said.

IATA represents 230 airlines accounting for 93 percent of scheduled international air traffic.

British Airways chief executive Willie Walsh told the conference the 2020 goal would mean "a significant cost to the industry, but there is no free lunch. We have to demonstrate our seriousness."

Eric Bachelet, president and chief executives of engine maker CFM International, said the adoption of biofuels was "moving much faster than we anticipated three, four years ago."

"The issue now is to jump-start the use of biofuel."

Zainal Adlin, an official of environmental group WWF-Malaysia and the tourism chief of Sabah, a Malaysian state famous for its wildlife, challenged the airline industry to do its part in halting climate change.

"You can play a pivotal role to make a difference but your voice must be collective," he said.

Bisignani, the IATA director general, told a news conference at the close of the two-day meeting that IATA was still finalising the cost of the 2020 programme and expected the figure "in a couple of weeks".

"These are substantial costs, so it's a burden. It's a strong burden for airlines, we are speaking of billions, it's something that would be painful, but we are taking full responsibility (for) our commitment."

On Monday, the IATA head said a new forecast pointed to a nine-billion-dollar loss for the airline industry in 2009 on top of a revised estimate of a 10.4-billion-dollar loss for 2008.

"This is the most difficult situation that the industry has faced," he said.

IATA says the industry spent 165 billion dollars on fuel in 2008, representing 31 percent of costs, because of high oil prices before the global economy was plunged into crisis.

The fuel bill is forecast to fall to 106 billion dollars in 2009 but industry executives fear there could be a new oil price spike on hopes of a US-led global economic recovery.