Sudan has summoned Egypt’s ambassador to Khartoum to protest Cairo’s “illegal” call for oil and gas exploration bids in the Red Sea area of Halayeb, claimed by both countries.

In a statement on Thursday, Sudan’s foreign ministry said it summoned Hossam Eissa over “tenders invited by the Egyptian oil ministry for areas under the sovereignty of Sudan”.

“Sudan is asking Egypt to stop all procedures concerning the tenders given the situation about the Halayeb triangle.”

It also warned oil and gas exploration companies against submitting any bids.

Egypt’s South Valley Egyptian Petroleum Holding Co has offered 10 oil and gas exploration blocks in the Red Sea for sale through a tender on March 10, with bids due to close on August 1.

The Halayeb triangle, which is controlled by Egypt, has been claimed by Sudan since the 1950s. Cairo says it is Egyptian territory and it has long been a source of contention between the two neighbours.

Badreddin Abdullah, undersecretary at the Sudanese foreign ministry, expressed Khartoum’s protest at the offer and called on Egypt “not to proceed in this direction that contradicts the legal status of the Halayeb triangle”, the ministry said in a statement.

On Wednesday, Saad al-Deen Hussein al-Bishri, minister of state at Khartoum’s Oil Ministry, said the move was “a direct intrusion” onto his ministry’s authority to grant exploration licenses in the area.

Relations between Cairo and Khartoum had turned sour in early 2017, when Sudan’s President Omar al-Bashir accused Egypt of supporting rebels in conflict zones, including Darfur in western Sudan.

Sudan in May 2017 banned the import of animal and other agricultural products from its northern neighbour.

But in October, it lifted the ban as ties improved following talks in Khartoum between Bashir and his Egyptian counterpart Abdel Fattah el-Sisi.

Egypt has this year repeatedly called for stability in Sudan after protests erupted on December 19 against Bashir’s three-decade rule.

Demonstrations and deadly clashes erupted after a government decision to triple the price of bread. Bashir has remained defiant, imposing a nationwide state of emergency on February 22.