DJIBOUTI, May 6 (Reuters) - Djibouti has accused Eritrea of violating its border in a worsening dispute over the Horn of Africa neighbours' shared frontier.
Djibouti says Eritrean soldiers entered its territory last month to dig trenches and build other defences. Eritrea has made no official comment.
"The violation of the border is flagrant. The two armies are facing each other. The situation is explosive," Djiboutian President Ismail Omar Guelleh told reporters late on Monday.
"We have asked for international arbitration from the Arab League and the African Union."
Eritrean officials were not available for comment.
Djibouti and Eritrea clashed over their border in the mid-1990s. On Saturday, the African Union called on both sides to show restraint and resolve any dispute with dialogue.
It said it was sending a fact-finding mission to the border and would consult officials from both countries.
Asmara fought a 1998-2000 border conflict with Ethiopia that killed some 70,000 people. The Red Sea state also fought a short war with Yemen in the mid-1990s over territory. (Reporting by Omar Hassan Awale; Editing by Jack Kimball) (For full Reuters Africa coverage and to have your say on the top issues, visit: http://africa.reuters.com/)