GENEVA - U.N. Secretary-General Antonio Guterres appealed on Monday for countries to step up aid pledges for Sudan, where a conflict between rival military factions has forced some 2.2 million people from their homes and sparked a major humanitarian crisis.

The United Nations says about $3 billion is needed this year for humanitarian relief inside Sudan and for refugees fleeing the country, only a fraction of which has been funded.

"Without strong international support, Sudan could quickly become a locus of lawlessness, radiating insecurity across the region," Guterres told a fundraising conference hosted by Germany, Saudi Arabia, Qatar, Egypt and the United Nations.

"I appeal to you all today to provide funding to deliver lifesaving humanitarian aid and support to people living in the most difficult and dangerous conditions," Guterres said.

Germany announced on Monday that it was pledging 200 million euros to Sudan and the region until 2024, and Qatar pledged $50 million, while the U.N. said it was allocating an additional $22 million to address priority needs.

The conflict between Sudan's army and the paramilitary Rapid Support Forces (RSF) began in mid-April amid tensions over an internationally-backed plan for a transition towards elections under a civilian government.

It has left more than 3,000 people dead, turned the capital Khartoum into a war zone and triggered deadly violence in the conflict-scarred western region of Darfur as well as other parts of the country.

Guterres said he was especially concerned by ethnic violence in Darfur and reports of gender-based and sexual violence. U.N. human rights chief Volker Turk said his office had received reports of sexual violence against at least 53 women and girls, saying that some 18-20 women were raped in a single attack.

Before the donor conference, a U.N. appeal for $2.57 billion for humanitarian support within Sudan this year was about 17% funded, a U.N. website showed.

More than half of that came from the United States, with the European Commission in second place with about 10% of the total. Saudi Arabia and Kuwait were also among the donors, the website showed, but with smaller amounts accounting to less than 1% of the total.

The U.N. has separately appealed for nearly $500 million in aid for refugees fleeing from Sudan, which U.N. refugee agency chief Filippo Grandi said was 15% funded, a situation he called "deeply distressing".

(Reporting by Emma Farge and Gabrielle Tétrault-Farber in Geneva; Writing by Aidan Lewis Editing by Christina Fincher)