Ethiopia is seeking further help from foreign donors after its estimates for the number of people needing food aid rose by 10%.
Rations have been cut as the government struggles to cope
The country's Disaster Prevention and Preparedness Commission said there are now 12.6 million in need.
The announcement comes just days after leading charities warned that shortfalls in donations to the UN food agency meant that millions of Ethiopia children were being "slowly starved".
Ethiopia hopes to stage its own Live Aid-style concert next month, with organisers seeking to raise $1.7m for famine relief. An appeal song is also planned.
There have been warnings that the situation could turn out to be worse than in 1984-85, when nearly one million people died.
Disaster Commission head Simon Machale said on Thursday that an extra 1.2 million Ethiopians needed food aid and that the country now required more than 250,000 tons to see it through to the end of the year.
A poorer than anticipated harvest in January was one of the reasons for the increased need.
Live Aid concerts in 1985 raised many millions for Ethiopia
The official denied that the revised figures meant that Ethiopia was facing a famine.
However he warned that if the food requirements were not met, that would be the result by the end of the year.
The BBC's Damian Zane in Addis Ababa says that some aid agencies are focusing on the country's long-term problems and calling for a rise in non-food assistance, such as agricultural input.
They argue the country could experience similar problems next year unless seeds and other basics are not distributed now.
On Monday, aid agencies working in Ethiopia accused donor communities of letting down millions of drought-stricken children.
Because of the humanitarian situation in Iraq, the needs of about 40 million people facing starvation across Africa were in danger of being ignored, UN World Food Programme head James Morris has warned.
Rations to the millions at risk in Ethiopia have been cut by as much as 20%, as the government tries to make limited supplies last.