Yet the nation that once co-ruled its southern neighbour, alongside the UK, has been almost entirely excluded from the continuing international drive to end Sudan’s latest bout of civil strife.
Analysts believe the perceived marginalisation of Egypt is partly a reflection of Cairo’s diminishing regional influence, which over the years has left ample room for the emergence of rising regional powers with the financial muscle and alliances to back their new clout.
“Sudan is undoubtedly the most important country to Egypt but its relations with Khartoum have been complex and sensitive for around 150 years,” said Mohamed Anis Salem, a former career diplomat who now sits on the Egyptian Council for Foreign Relations, a think tank in Cairo.
“The region has gone through structural change and there are more energetic and dynamic countries now that have chipped away at Egypt’s regional standing and are happy to play an active role and cope with the cost of doing that."
On Thursday, the army and the RSF agreed to a deal mediated by Saudi Arabia and the US that commits them to allowing safe passage for civilians, medics and humanitarian relief, and to minimise harm to civilians and public infrastructure.
US officials said the deal would be followed by negotiations on the details of securing humanitarian access accompanied by a ceasefire of up to 10 days.
The fighting, which began on April 15, has killed at least 750 people and injured about 5,000 to date.
It has forced another 200,000 to take refuge in neighbouring countries. At least 60,000 of these fled to Egypt, while most of the others went to Chad and Ethiopia.
Egypt and Sudan have long been bound by close ties, with a rich mass of social, economic and cultural relations.
Their political ties, however, have consistently proved less durable than those between the people of the two nations.
The larger and more powerful Egypt has always viewed Sudan as vital to its national security because of its 650km Red Sea coastline, its control of the middle reaches of the Nile, the source of nearly all of Egypt’s freshwater needs.
Sudan’s territory also stretches east to the increasingly strategic Horn of Africa, west to the troubled Sahel region and south to central Africa.
But repeated attempts over the past 50 years to integrate the two countries’ economies or place them on the path to a full union, have made little headway amid concerns held by many Sudanese that their country would be swallowed by its bigger neighbour.
More recently, Egypt and Sudan have been working on a rail link and on integrating Sudan into Egypt’s national electricity grid to help it overcome its chronic power shortage.
The two nations’ militaries have been conducting frequent joint war games. Their governments have for years synchronised their approach to talks with Ethiopia over the construction by Addis Ababa of a Nile dam that both Cairo and Khartoum regard as a threat to their water security.
Yet Egypt has not been part of the international diplomatic push to calm the conflict in Sudan.
Egypt 'didn't have a role'
“I am not sure the Egyptians were left out of the process per se, but they definitely didn’t have a designated role to play,” said Michael Hanna, a Middle East expert and the New York-based director of the US programme at the International Crisis Group.
“They were consulted but they were not part of the process.”
He said Egypt was mostly to blame.
Egypt and Sudan have been on-and-off allies for decades, with Cairo enjoying its closest ties with Khartoum when the Sudanese military is in power.
Egypt's relations with Sudan have been fraught with tension and distrust every time an elected government was in power in Khartoum.
Ruled by men with a military background for most of the 70-plus years since the monarchy was toppled, Egypt has thrown its weight behind Gen Abdel Fattah Al Burhan, the army chief who in 2019 became Sudan’s de facto head of state.
Egypt continued its support for Gen Al Burhan even when he and RSF commander Gen Mohamed Dagalo seized power in a 2021 coup that was condemned by the international community for derailing Sudan’s democratic transition and plunging the nation into political and economic crisis.
“There is a foreign and domestic constant in Egypt these days, which is the supremacy of the state and its institutions and the need to protect them,” said Mr Salem, echoing Egyptian President Abdel Fattah El Sisi, himself a former army general who was first elected in 2014.
“The preservation of the state means continuity.”
Cairo has also failed to join foreign powers in their denouncement of the heavy-handedness shown by Sudan’s security forces when dealing with the anti-military street demonstrations that swept the country after the 2021 coup.
At least 120 were killed and more than 2,000 injured in those protests.
Egypt's alienation of the pro-democracy forces campaigning for a return to civilian rule was complete when it sought last year to broaden the participation of civilians in the internationally backed process to find a way out of the political crisis created by the 2021 coup.
It invited supporters of former president Omar Al Bashir — deposed by his generals in 2019 amid a popular uprising against his 29-year rule — and representatives of parties loyal to Cairo to meetings in the Egyptian capital, a move that deeply angered the pro-democracy movement and raised eyebrows among the movement's foreign backers
“The Egyptians were never fully on the same page with the transition,” said Mr Hanna. "That in turn burnt some bridges and upset some key members of the international community."
With Sudan now embroiled in fighting, Egypt has lost a key ally in its dispute with Ethiopia over the Grand Ethiopian Renaissance Dam.
Talks between Ethiopia on one side and Sudan and Egypt on the other collapsed in 2021, with Cairo and Khartoum insisting that Addis Ababa enters a legally binding agreement on the operation and filling of the dam. Ethiopia maintains that guidelines should suffice.
“The exit of Sudan from the renaissance dam equation loses Egypt a source of support it has long counted on,” said Amani El Taweel, one of Egypt’s most authoritative analysts on Sudan.
“Egypt also lost tools of pressure on Ethiopia now that joint air and naval war games with Sudan are off."
Darfur at risk
Another source of concern for Egypt is the possibility of Sudan fracturing, with the restive western region of Darfur most at risk in the case of a protracted conflict or the defeat in Khartoum of Gen Dagalo’s RSF.
Both Gen Dagalo and his RSF come from Darfur where, back in the 2000s, they fought on the government’s side against ethnic African rebels. The vast region would be the obvious place for the general and his men to fall back on in defeat.
Darfur is already the scene of fierce battles between troops and RSF fighters in addition to tribal and ethnic clashes. The security vacuum created by the fighting has also given rise to tribal clashes in the Kosti region south of Khartoum.