The United Nations is sounding the alarm about a devastating famine in parts of war-torn Somalia that has already seen tens of thousands stream out of the country and thousands more perish.

Mark Bowden, the UN's humanitarian coordinator in Somalia, says the famine is getting worse and putting many more lives at risk.

"Somalia is facing its worst food security crisis in the last 20 years," Bowden told journalists in Nairobi, Kenya on Wednesday. "This desperate situation requires urgent action to save lives."

For now, the UN is declaring famine in two regions of southern Somalia: southern Bakool and Lower Shabelle. But Bowden says it action isn't taken immediately, "famine will spread to all eight regions of southern Somalia within two months."

The crisis in Somalia has resulted largely from a severe drought in the Horn of Africa -- thought to be the worst in 60 years -- but it has been exacerbated by the ongoing conflict in Somalia.

The famine is thought to be the worst since 1991-92, when hundreds of thousands of Somalis starved to death, Bowden said. That famine prompted intervention by an international peacekeeping force. But forces eventually pulled out after two American Black Hawk helicopters were infamously shot down in 1993.

The conflict in Somalia has continued to rage since, with al Shabaab Islamist rebels in control of much of its southern lands.

Grasping the full scope of the situation has been difficult. Somali militants had banned aid agencies from operating in these areas until earlier this month.

The UN believes that six people are dying each day from famine in some parts of Somalia, while more than half of the children in these same areas are malnourished.

Those startling figures already exceed the official definition of famine, which is declared when two adults or four children per 10,000 people die from hunger a day, and when one-third of children are malnourished.

The same drought that has led to famine in Somalia has also badly affected people living in neighbouring Djibouti, Ethiopia and Kenya.

Kevin McCort, the head of CARE Canada, said the famine has left desperate Somali families trekking into swollen refugee camps in Kenya and Ethiopia, seeking relief.

"What we're witnessing is a steady flow of 1,000 to 1,500 people every day coming into those camps," McCort told CTV's Canada AM from Nairobi, Kenya, during a telephone interview on Wednesday.

But a major camp in Dadaab, Kenya, that was built for 90,000 people now has more than 400,000 refugees at its doorstep. And that number is increasing every day.

Canada urged to donate more

Bowden said the UN needs more resources to give suffering Somalis the food, clean water, shelter and health services needed to help them survive.

He said the UN is seeking US$300 million within the next two months, though the British aid group Oxfam says as much as $1 billion will be needed to fund relief efforts through to January.

Canada has already pledged $22 million in humanitarian aid to the region so far this year, with half of that allocated specifically to Somalia, Kenya and Ethiopia. But Oxfam Canada is calling on Canada to up the ante. It wants Canada to pledge at least $40 million.

International Co-Operation Minister Bev Oda is expected to make a funding announcement on Friday.

Several western countries have pledged additional funds for the famine crisis, with Britain leading the pack with a $145-million pledge for emergency aid. The United States has so far offered an additional $28 million in aid, while Spain ($10 million), Germany ($8.5 million) and the European Union ($8 million) have made promises of their own.

But Oxfam regional director Fran Equiza says the money being offered still isn't enough to stop the famine before it is too late.

"There is no time to waste if we are to avoid massive loss of life," Equiza said in a statement released Wednesday.

"We must not stand by and watch this tragedy unfold before our eyes. The world has been slow to recognize the severity of this crisis, but there is no longer any excuse for inaction."

Somalia has long been considered the most dangerous country in the world to work in. The UN's World Food Program has lost 14 relief workers in the past few years in the country, as killings and attacks on aid convoys occur frequently.

Two years ago, the WFP pulled out of southern Somalia, after the rebels demanded cash payments and other concessions.

With files from The Associated Press