The figure was revealed in a Senate estimates hearing on Monday after questions from the Greens.

The government has mounted a massive international effort to avoid UNESCO's world heritage committee listing the reef as officially in danger next month.

That has included establishing a dedicated taskforce within the Department of Foreign Affairs and Trade and travelling to each of the 21 countries on the committee.

The hearing heard the government had met with officials in 19 of the countries, with only Algeria and Senegal remaining.

The environment department's deputy secretary Kimberley Dripps told the hearing that just under $100,000 had been spent to pay for department staff to conduct talks in countries including Japan, Korea, India, Germany, Croatia, Lebanon, Turkey and Malaysia.

The figure does not include travel costs for Environment Minister Greg Hunt or Australia's ambassador for the environment Peter Woolcott.

Greens environment spokesman Larissa Waters said on Monday the government should not be spending money on lobbying efforts but on addressing the recommendations of the world heritage committee, which called for Australia to substantially increase protections for the reef.

Since draft recommendations were published last year, the government has banned the dumping of dredge spoil in the Commonwealth marine park area, which was a major issue of concern for the committee.

Environment groups, which have run a huge global campaign against coal projects near the reef, say this is not enough and industrial projects should be stopped.

The government has published a management plan for the reef to address issues such as water quality, but which has attracted criticism for its lack of focus on climate change.

"What the reef needs right now is action, not overseas lobbying trips," Senator Waters said.

"To show real action to save the reef, the minister should revoke his approval of the world's largest coal port in the Great Barrier Reef at Abbot Point, and introduce credible climate policies."

The International Union for Conservation of Nature will make a draft recommendation on the reef's status at the end of this month, which will be followed by the world heritage committee's decision in June.

On Monday, Greenpeace welcomed moves by Mr Hunt to push for extra funding for reef protection in Tuesday's budget but said this fell short of the action needed to save the reef from an in-danger listing.

Greenpeace said Mr Hunt had to turn his attention to protecting the reef from expansion plans by the fossil fuel industry on the Queensland coast.

"The largest looming threat to the reef is the planned coal industry expansions along the Queensland coast, plans that will send more ships through the reef's sensitive waters, create a higher risk of shipping accidents and drive climate change," Greenpeace campaigner Shani Tager said.

Mr Hunt said the government had addressed "every single concern raised by the World Heritage Committee in 2011 when the Greens were in power with Labor".

He added that the government was spending $2 billion over the next decade on reef protection, had banned the dumping of dredge waste and had established a reef trust to invest in projects to protect the reef.

"The Greens want the reef delisted. We don't," Mr Hunt said.

"We make absolutely no apology for defending the reputation of Australia's great natural icon on the world stage. It would be irresponsible and negligent not to back our strong action with a focus on protecting the reputation of this great icon.

"By contrast, it's disgraceful the Greens and their supporters are determined to trash the reef's reputation with untruthful and unfounded smear as part of a campaign to have it delisted."

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