Sudan summoned Egypts ambassador to Khartoum on Thursday to protest Cairos "illegal" call for oil and gas exploration bids in the Red Sea area of Halayeb, claimed by both countries. Egypts control of the Halayeb triangle, which lies in a mineral-rich border region, has for decades been a bone of contention between Cairo and Khartoum, despite an overall improvement in ties since an October summit. On March 10, Egypts state-owned South Valley Egyptian Petroleum Holding Company invited bids for 10 oil and gas exploration blocks in what it said were Egyptian territorial waters in the Red Sea. "The foreign ministry summoned the Egyptian ambassador Hossam Eissa on Thursday to protest against the tenders invited by the Egyptian oil ministry for areas under the sovereignty of Sudan," Sudans foreign ministry said in a statement. "Sudan is asking Egypt to stop all procedures concerning the tenders given the situation about the Halayeb triangle." Sudan has regularly protested at Egypts administration of Halayeb and the Shalatin border region near the Red Sea, saying they are part of its sovereign territory since shortly after independence in 1956. On Wednesday, Sudan urged Egypt to withdraw its offer of exploration blocks. On Thursday, the foreign ministry summoned the Egyptian ambassador and urged international companies working in the area to not to submit bids for the blocks. It called on Cairo to resolve the situation "through peaceful means" to avoid damaging the improving ties between the two countries.