Sudan says government-backed Ethiopian militiamen killed five women and a child during a raid just inside its territory, further fuelling tension in the border region. On Wednesday, Sudan warned of “dangerous consequences” for bilateral relations after an Ethiopian warplane breached Sudanese airspace in the border area, according to a foreign ministry statement. It did not specify the type of Ethiopian aircraft or say how long it stayed inside Sudanese airspace. “The Foreign Ministry condemns this escalation by the Ethiopian side and demand that such acts are not repeated in the future,” it said. Also on Wednesday, a Sudanese military helicopter crashed while attempting to land at an airport in the eastern Qadaref region at the end of what the military said was a reconnaissance mission. The two-man crew, both flight captains, survived the crash, it added without giving more details. It was not immediately clear whether the helicopter crew’s mission was related in any way to the tension on the border with Ethiopia. Ethiopia’s alleged aerial intrusion came one day after Addis Ababa warned Khartoum that it was running out of patience with its continued military build-up in the border region, an area at the centre of a decades-old territorial dispute. The two countries have been sharply at odds over a Nile dam being built by Ethiopia. Ethiopia warned Sudan that it was running out of patience with its continued military build-up in the border region, an area at the centre of a decades-old territorial dispute. The area in question, Al Fashqa, is within Sudan's international boundaries, but has long been settled by Ethiopian farmers, and late last year suffered weeks of clashes between forces from the two sides. "The Sudanese side seems to be pushing in so as to inflame the situation on the ground," Ethiopian foreign ministry spokesman Dina Mufti said on Tuesday. "Is Ethiopia going to start a war? Well, we are saying let's work on diplomacy." On the same day, Sudan's foreign ministry strongly condemned the militia raid in its eastern breadbasket Qadaref region and called on the international community to work for the cessation of such actions. It blamed the raid on the Al Shifta militia, an outfit widely believed to enjoy the informal backing of the Ethiopian military. Two Sudanese women were also missing after the Monday raid, the government said. Monday's raid was the latest in a series of violent incidents in recent weeks in the border region. Sudanese troops moved to retake border areas long held by Ethiopia and defended by government-linked militias, who also allegedly operate smuggling rings. The fighting in Ethiopia's Tigray region forced at least 50,000 of its residents to flee their homes and seek refuge in Sudan. Ethiopia accuses the Sudanese military of infiltrating its territory, saying Sudan was seeking to take advantage of the conflict against separatist rebels in Tigray. Sudan’s information minister Faisal Saleh denied the Ethiopian charges. "We fear that these comments contain a hostile position towards Sudan," Mr Saleh said. "We ask of Ethiopia to stop attacking Sudanese territory and Sudanese farmers." He also said late on Tuesday that a joint committee set up last month to resolve differences over the border has so far failed to make any progress. Sudan and Ethiopia have long had problems along their porous border, whose demarcation was determined in agreements reached early in the last century. The two countries are bound by close cultural ties but, in various conflicts since the 1950s, both sides have supported rebel groups fighting the other’s government. The latest round of tension on the Sudanese-Ethiopian border, however, comes at a critical time in relations. The latest round of tension on the border, however, comes at a critical time in relations. Sudan is seething over Ethiopia's recent announcement that it would go ahead with a second filling of the water reservoir behind the Grand Ethiopian Renaissance Dam, starting this summer. According to Addis Ababa, this would happen regardless of whether an agreement on the operation of the dam was reached with downstream Sudan and Egypt. Ethiopia began the initial filling of the dam last summer, without giving prior notice to either Egypt or Sudan. The nearly complete hydroelectric dam, Africa’s largest, is built less than 20 kilometres from the border with Sudan and on completion, is expected to generate 6,000 megawatts of power. For Sudan, the absence of co-ordination on the operation of the dam could potentially spell disaster for its eastern region, through flooding and the disablement of its own hydroelectric dams on the Nile. For Egypt, the dam could mean a significant reduction in its vital share of the Nile’s waters, something Cairo says it will not tolerate. Sudan and Egypt have been trying to persuade Ethiopia to enter a legally binding deal on the operation of the dam as well as agree on mechanisms for resolving future disputes. Ethiopia favours recommendations, rather than a binding deal. The latest round of negotiations on the dam collapsed this week when Sudan insisted that experts from the African Union be given a greater role in drafting an agreement. Ethiopia and Egypt rejected the suggestion, insisting the three nations must maintain ownership of the negotiating process.