Muslim clerics in Egypt, Morocco, Yemen and Saudi Arabia rule zakat or mandatory alms can be donated directly by Muslims for relief work, UN High Commission for Refugees says.
The UN has started a scheme allowing Muslims to make donations from the alms they typically pay state bodies for the benefit of the poor.
Muslims around the world are expected to pay typically 2.5 percent of any savings accumulated over the year as "zakat" or contribution to social welfare. They generally pay such alms via state institutions, collecting funds to help impoverished citizens.
But after consulting with leading Islamic scholars and institutes, Tabah Foundation of Abu Dhabi in the United Arab Emirates (UAE) concluded that the UN High Commission for Refugees (UNCHR) can collect and distribute zakat provided that they fulfil the basic requirements of one of the legal schools of thought.
Zakat is typically believed to be eligible if paid to Muslims in need.
The UNHCR said it had obtained religious rulings from top Muslim clerics in Egypt, Morocco, and Yemen as well as a senior Islamic scholar in Saudi Arabia to donate their alms directly for relief work.
The UNHCR said it hoped would persuade wealthy Muslims, especially in oil-rich Gulf countries.
"It is an innovation in our efforts to raise funding," said Muhammed Abu Asaker, a UNHCR Middle East spokesman.
Millions of Syrians, Iraqis, and Yemenis have been displaced by years of civil war, sometimes to neighbouring countries, straining the host countries' resources as well as the UN, donor countries and other non-governmental humanitarian agencies' funds.
How much needed?
The UN has projected it will need a total of $8 billion this year to provide life-saving assistance to millions of Syrians inside their shattered homeland and to refugees and their host communities in neighbouring countries.
UNHCR has also called for $2.1 billion to provide food, and medicine for Yemen, where 12 million people are at risk of famine and cholera brought on by two years of civil war.
UNHCR said it will use some of the additional funds it expects from the alms project to help some 30,000 of the most vulnerable Syrian refugee families in Jordan, with around $180 in monthly cash support for each family.
"The needs of these people increase daily and because the crises are ongoing, for example, the Syrian crisis is entering its 7th year," Abu Asaker said.
"So anything these people had is not completely gone and they need continuous support. So this requires us as an organisation to search for creative ways that go in parallel with governmental support, which has become insufficient given the rising number in refugees and IDPs (internally displaced people)."
The amount of zakat money distributed each year in Muslim countries ranges from $20 billion to $30 billion, experts say.
Zakat payments can be a matter of personal choice in many Muslim countries, though it is a religious obligation under Islamic law.
Governments in some countries deduct payments from savings accounts on a pre-determined day. The funds tend to be used to help those in poverty, in debt or refugees.
The UNHCR posted the rulings on its web page which makes an appeal for zakat contributions to aid programmes.