By Mubasher Bukhari

ISLAMABAD, April 20 (Reuters) - Pakistan has put a $1.5 billion deal to supply weapons and jets to Sudan on hold after Saudi Arabia asked for the agreement to be terminated and said it would not finance the purchase, two Pakistani security sources and a diplomatic source said.

The conflict between Sudan's army and the paramilitary Rapid Support Forces has stoked the world's worst humanitarian crisis for around three years, turning into a flashpoint for competing foreign interests and threatening to break up the Red Sea country, a major gold producer.

Reuters first reported a deal was in the final stages in January and had been brokered by Saudi Arabia, but no financing from Riyadh was disclosed at the time. The deal was among several defence sales being negotiated by the Pakistani military after its jets and weapons systems gained prominence following skirmishes with India in May last year.

Saudi Arabia is one of Pakistan's closest allies and has been a source of critical loans and financing for Islamabad's ailing economy. Their relationship has deepened since the signing last year of a mutual defence ​pact treating aggression against either as an attack on both.

"Saudi Arabia has signaled that Pakistan should terminate the deal after it dropped the idea of financing it," one of the security sources said.

The Saudi government media office did not immediately respond to a request for comment. Sudan's armed forces also did not immediately respond.

The Pakistani military did not respond to a Reuters request for comment. The military and air force had not previously confirmed that a deal was in the pipeline.

The source added that some Western countries had advised Riyadh to stay away from proxy wars in Africa.

Saudi Arabia and the United Arab Emirates have backed opposing sides in conflict-ridden countries across the region, including in Sudan.

While both sides say they back a diplomatic resolution to the conflict, Saudi Arabia has put its weight behind Sudan's army, while the UAE has been accused of providing logistical support to the RSF, a charge it officially denies.

The source said a March meeting between Sudan army leaders and Saudi authorities in Riyadh resulted in the termination of Saudi financing for the deal.

Another $4 billion deal with the Libyan National Army, reported by Reuters in December, was also in jeopardy because the Saudis are "revisiting their strategy" in both countries, the second security source said.

(Reporting by Mubasher Bukhari; Additional reporting by Ariba Shahid and Saad Sayeed in Islamabad, Timour Azhari in Dubai and Khalid Abdelaziz; Editing by Sharon Singleton)