“If we don’t take the necessary measures, famine will be the scandal of this century,” AFP news agency quotes Bruno Le Maire as saying in Rome.
More than 10m people are thought to be at risk of starvation and famine has been declared in two areas of Somalia .
The UN chief has urged donor nations to supply an extra $1.6bn (£980m) in aid.
Earlier the Red Cross said it delivered food to one of Somalia’s worst-hit areas, controlled by Islamists.
Working through a local committee, the Red Cross delivered lorry-loads of food for 24,000 people.
‘Question of life and death’
Al-Shabab, an al-Qaeda-affiliated group which controls large swathes of south and central Somalia, had imposed a ban on foreign aid agencies in its territories in 2009, but has recently allowed limited access.
AnalysisAndrew HardingAfrica correspondentThere are dozens of experienced local aid organisations already working throughout Somalia – a fact that often gets lost in the furore over al-Shabab’s hostile attitude towards some of the bigger international organisations, like WFP.
There’s no doubt that the drought – and the Arab spring – have shaken up the security situation in Somalia.
Anecdotal evidence suggests al-Shabab is now seriously short of money, more divided than ever, and many of the foreign jihadist fighters who came to join it have left the country for other struggles.
But the World Food Programme says it still cannot reach 2.2 million people inside Somalia as refugees continue to pour over the Kenyan and Ethiopian borders.
The UN says East Africa is experiencing the worst drought in 60 years. Somalia is thought to be worst-hit, but Ethiopia and Kenya have also been affected.
Analysts say the drought has been caused by the lack of rains and the failure of governments to adequately finance agriculture and irrigation schemes.
The meeting of ministers from the G20 nations at the UN’s Food and Agriculture Organisation headquarters in Rome was requested by France, the current chair of the G20 group of powerful economies.
“Our meeting is a question of life or death for tens of thousands of people,” Mr Le Maire said at the start of the meeting, AFP reports.
Bob Geldof and other celebrity activists are urging the international community to come up with more cash.
They accuse some countries, Italy, France, the Arab states and Germany, of contributing too little in proportion to their national wealth.
Ahead of the summit, the World Bank announced plans to provide more than $500m to relieve the crisis for projects from Djibouti to Kenya.
Ethiopia safety-net
Mr Le Maire told the BBC said the first aim of the meeting was to co-ordinate the aid and response to the crisis.
“The second goal is also to think about the future and the long-term perspective because what we see here in Africa is that people need to have their own food and to have their own agriculture,” he said.
BBC Africa analyst Martin Plaut says many people at the heart of the current disaster in Ethiopia have emerged relatively unscathed.
This is because the government in Addis Ababa has such an extensive safety-net in place, he says.
Pre-positioned supplies mean the Ethiopian authorities could respond rapidly once the extent of the drought became clear.
The first food distributions began in February and have continued to the worst effected communities across a vast area.
Communities are suffering, but the famine that has hit neighbouring Somalia has so far been avoided and the overall the disaster management system, built up since the 1980s has worked.