The British Middle East Eye website quoted sources as saying that last week hundreds of Sudanese soldiers arrived in Saudi Arabia, on their way to Yemen, indicating that Khartoum is increasing its participation in the war.
Sudan had announced in January that it would reduce its military presence in Yemen from about 5,000 soldiers to a "small" group of about 650 soldiers, after it was participating with up to 15,000 soldiers deployed there as part of the Saudi-UAE-led coalition to fight Al Houthi group.
Private Saudi sources told Middle East Eye that 1,018 Sudanese army officers and soldiers entered the kingdom by sea on September 22, and reached the southeastern city of Jizan, near the Yemeni border.
An informed source - who requested anonymity due to the sensitivity of the issue - said that two Sudanese planes carrying military personnel left Khartoum to Najran airport in southern Saudi Arabia the day before the arrival of the naval regiment.
Former Sudanese President Omar al-Bashir had decided to participate in the war in Yemen alongside Saudi Arabia in 2015, to help Yemeni President Abd Rabbu Mansour Hadi regain power, and Sudanese forces were particularly active in the country's coast on the Red Sea.
Since the overthrow of Al-Bashir's government 1.5 years ago, the new rulers - a mixture of civilians and military personnel - have begun to push the Sudanese forces out of Yemen, yet several hundred RSF forces remain in Aden - controlled by the UAE - and on the Saudi-Yemeni border.
And last week, Sudanese media reported that the RSF had sent 28 civilians from West Darfur to fight in Yemen.