Yemen told a donor meeting on Tuesday it needs almost $12 billion dollars in the short term to weather a rough political transition triggered by Arab Spring protests.

"The national unity government needs $11.9 billion in the short term," Planning and International Cooperation Minister Mohammed al-Saadi told delegates at the meeting in the Saudi capital.

The government "urgently needs to spend $4.7 billion on serious humanitarian needs by February," he said.

Saudi Finance Minister Ibrahim al-Assaf opened the meeting with a call for more aid to the kingdom's impoverished southern neighbour. "Yemen is facing many economic problems ... The kingdom hopes to see more contributions," he said.

Oil-rich Saudi Arabia already pledged $3.25 billion in aid at a Friends of Yemen meeting held in its capital last May at which a total of $4 billion was pledged.

Assaf and Saadi on Tuesday signed three agreements detailing the Saudi aid package, which amounts to a $1 billion deposit in Yemen's central bank, a $1.75 billion grant, and $500 million to fund and guarantee Saudi exports to Yemen.

The World Bank has said it hopes to raise $6 billion at the latest donor meeting to support the recovery plan put together by the transitional government in Sanaa.

"We hope to raise $6 billion during the donor meeting to cover the transition period lasting until the middle of 2014," said Wael Zakout, the World Bank's country manager for Yemen on the bank's website.

"We will hold another donor conference after 2014 to raise the rest of the needed funds," he said.

Rajiv Shah, administrator of the US development fund USAID, said his country was providing $345 million in aid to Yemen this year, going to "security, humanitarian and development assistance."

"Over half of our support is for political transition, humanitarian assistance and development. The majority of the amount, $117 million, is for humanitarian assistance," he said.

The two-day Riyadh meeting aims to address several issues, including reconstruction, humanitarian needs and ways to strengthen security and stability in Yemen, Saadi told reporters in Sanaa ahead of the conference.

It will also cover political dialogue, preparations for elections and basic infrastructure needs, he said, adding some states would pledge aid in Riyadh and other await a Friends of Yemen meeting in New York next month.

Yemen is undergoing a political transition after a year-long uprising unseated veteran leader Ali Abdullah Saleh and left the economy of the Arabian peninsula's poorest country in shambles.

But so far only 43 percent of $455 million earlier asked for by the United Nations and other organisations has been received for humanitarian aid for Yemen.

The Friends of Yemen forum was set up at an international conference in London in January 2010 to help Sanaa combat a resurgent Al-Qaeda threat in the ancestral homeland of its slain chief Osama bin Laden and other security challenges.

The IMF says the 2011 political crisis has taken a serious toll on the Yemeni economy, which it said contracted by 10.5 percent, while inflation had soared to 17.6 percent.

Aid agencies say nearly half of Yemen's 10-million population do not have enough food to eat, and one in three children is severely malnourished.