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 Senegal reopened borders with the worst-hit countries -- 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 over 5,100 people in Guinea, Liberia and Sierra Leone, the 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 IMF's initiative to release $300 million 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 for Ebola at the Nebraska Medical Center in Omaha.
The G20 pledge came as Togo, which is coordinating the west African fight, warned the world "cannot relax efforts" despite some encouraging reports from west Africa.
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 announcement came a day after Liberia lifted its state of emergency, announcing huge gains in fighting Ebola.
But attention has now turned to Mali where there are fears 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.
Mali has placed 256 people under observation and teams of investigators are tracing health workers and scouring Bamako and the imam's home village of Kouremale, which straddles the border with Guinea, for possible cases.
Former colonial power France said it was including Bamako in its list of destinations subject to Ebola flight checks, and the French development minister, Annick Girardin, was to make an unscheduled visit to Mali on Saturday.
"The situation in Mali is worrying," she told AFP in Conakry. "I have decided to travel tomorrow to Bamako to 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 Organization said 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.
UN Secretary-General Ban Ki-moon warned Saturday that Ebola could potentially provoke a food crisis affecting a million people across the region, by disrupting farming.
"As rates decline in one area, they are rising in others. Transmission continues to outpace the response from the international community," Ban told reporters.
"I urge the leaders of G20 countries to step up," he said.
A joint petition from aid groups including Oxfam and Save the Children urged the G20 to band together to ensure the right resources are made available in terms of staff, equipment and funding.
"This is a chance to stop Ebola in its tracks, and it must not be missed," said Oxfam Australia chief Helen Szoke.
Artists including One Direction, U2 frontman Bono, Coldplay's Chris Martin and Sinead O'Connor were joining forces against Ebola in London by recording a 30th anniversary version of the Band Aid charity single "Do They Know It's Christmas?".
Ebola "is a particularly pernicious illness because it renders humans untouchable and that is sickening," Bob Geldof -- one of the champions of the original Band Aid -- said this week.
"Mothers can't comfort their children in their dying hours. Lovers can't cradle each other. Wives can't hold their husbands' hands," Geldof said.
This will be the fourth incarnation of the song, which became one of the world's biggest-selling singles ever after its release in 1984 to raise funds for famine relief in Ethiopia.