Brisbane - The world's most powerful economies vowed on Saturday to "extinguish" the Ebola epidemic ravaging west Africa, as the vast desert nation of Mali scrambled to prevent a new outbreak of the killer disease.
Despite some hopeful signs from Africa - where Liberia has lifted its state of emergency and the Democratic Republic of Congo announced the end of its own, unrelated, outbreak of Ebola - the recent deaths of three people in Mali have fuelled fears of a new hotspot.
As pop stars recorded a new "Band Aid" single in London to help combat a disease that has killed more than 5 100 people in Guinea, Liberia and Sierra Leone, global leaders meeting in Brisbane made no new pledges of cash.
"G20 members are committed to do what is necessary to ensure the international effort can extinguish the outbreak and address its medium-term economic and humanitarian costs," the leaders said in a statement, as they welcomed the International Monetary Fund's initiative to release $300m to combat Ebola.
They also promised to share best practices on protecting health workers on the frontline, as a Sierra Leone doctor with US residency was flown to be treated at the Nebraska Medical Center in Omaha.
Described as "critically ill", Martin Salia will be the third Ebola patient treated at the facility. Both others survived.
"We immediately started preparing the unit and notifying staff members of this possibility," said Phil Smith, medical director of the bio-containment unit.
"We've obviously been through this a couple of times before, so we know what to expect."Mali situation worrying
The G20 pledge came as Togo, which is coordinating the west African fight, warned that the world "cannot relax efforts" despite some encouraging signals on the ground.
Senegal said on Friday it was reopening its air and sea borders with Guinea, Liberia and Sierra Leone, although its land border with Guinea will remain closed. The news came a day after Liberia lifted its state of emergency, announcing huge gains in fighting Ebola.
The Democratic Republic of Congo - where a three-month outbreak of a different strain of the disease claimed at least 49 lives since August - declared itself Ebola-free on Saturday.
But attention has now turned to Mali where there are fears that an isolated outbreak could spark a major crisis after the deaths from Ebola of three people infected by a Guinean imam who died of the disease.
A fourth person, a doctor at the Bamako clinic where the cleric died, is in intensive care with Ebola. More than 250 people have been placed under observation.
Former colonial power France added Bamako to its list of destinations subject to Ebola flight checks, and its development minister, Annick Girardin, was to make an unscheduled visit to Mali on Saturday.
"The situation in Mali is worrying," she told AFP in the Guinean capital Conakry, saying she would "meet the Malian authorities to see how we can scale things up."
There is no known cure for Ebola, one of the deadliest known pathogens which spreads through contact with bodily fluids, but trials for several possible treatments were announced this week in west Africa and Canada.
The World Health Organisation said on Friday that 5 177 people are known to have died of Ebola across eight countries, out of a total 14,413 cases of infection, since December 2013.Makes humans 'untouchable'
UN Secretary-General Ban Ki-moon urged "G20 countries to step up", warning that Ebola's disrupting effect on farming could potentially spark a food crisis for a million people.
"As rates decline in one area, they are rising in others. Transmission continues to outpace the response from the international community," Ban told reporters.
A joint petition from aid groups including Oxfam and Save the Children urged the G20 to band together to ensure that the right resources are made available in terms of staff, equipment and funding.
Artists including One Direction, U2 frontman Bono, Coldplay's Chris Martin and Sinead O'Connor were set to record late into the night for a 30th anniversary version of the charity single Do They Know It's Christmas?.
"It's not just about what's happening in west Africa, it could happen here tomorrow," said rocker-turned-activist Bob Geldof, one of the forces behind the original Band Aid.
"We can stop this thing, we can allow mothers no matter where they are to be able to touch their dying children."
Making his way into the studio, Bono hit out at the response of rich countries, saying if they "kept the promises they make at these big G8 meetings and the like we wouldn't have to be standing here".
Set to air on Sunday before its official release Monday, the single will be the fourth incarnation of the song, which became one of the biggest-selling singles ever after its release in 1984 to raise funds for Ethiopian famine relief.