ADDIS ABABA, Ethiopia (AP) — Djibouti has lodged a formal complaint with the African Union accusing soldiers from neighboring Eritrea of occupying a contested mountainous area after Qatari peacekeepers left the region this week, an official said.

The move threatens to renew a territorial dispute between the two East African nations that Qatar, now caught up in a diplomatic clash with other Arab nations, has helped to mediate.

ADVERTISEMENT

“The Eritrean troops occupied the Dumeira Mountain immediately after Qatar’s peacekeepers left,” Djibouti’s ambassador to Ethiopia, Mohammed Idriss Farah, told The Associated Press. “Sometimes the Eritrean troops go to the top of the mountain and return on the other side. What makes this one different is that they moved in right after the peacekeepers left.”

The ambassador said his government was waiting for military confirmation on whether Eritrean forces still controlled the contested area.

A spokesman for the African Union, Ebba Kalondo, confirmed that Djibouti had officially lodged a complaint to the AU Commission. On Friday evening, AU chairman Moussa Faki Mahamat said on Twitter that the continental body would send a delegation to the border to monitor developments and “work with all parties.”

U.N. spokesman Stephane Dujarric said the United Nations has received written communications from Djibouti and Eritrea “and we’re taking a look at it.” He did not disclose the contents but called the incident “an example of the spill-over effect” from the dispute between Qatar and Saudi Arabia and other Gulf countries.

Qatar said Wednesday it had pulled all of its troops from the Djibouti-Eritrea border. That came after Eritrea expressed support for the Saudi-led move to isolate Qatar amid a diplomatic dispute.

Qatar has helped to mediate the long-running Djibouti-Eritrea territorial dispute. Eritrea in the past has clashed with both Djibouti and Ethiopia over borders.

Eritrean officials could not be reached for comment. Eritrea’s top diplomat to the AU on Wednesday said the country wants to solve the problem with Djibouti peacefully.

A spokesman for Eritrea’s biggest armed opposition group, Nasredin Ali, said Eritrea sent two battalions to control the contested area. “They have met no resistance from Djibouti’s forces.”