Morocco has asked the United Nations to close a military liaison office in Western Sahara, a spokesman for the organization said on Monday, an indication that an escalating dispute between the Moroccan authorities and Secretary-General Ban Ki-moon over the disputed territory is not abating.

The request came a day after dozens of civilian staff members of a United Nations peacekeeping mission in Morocco that is known by the acronym Minurso left the country under threat of expulsion by the Moroccan authorities, who are furious over comments by Mr. Ban this month describing Western Sahara as occupied.

Morocco has long asserted sovereignty over the vast southern region, where Minurso has been deployed for a quarter-century, helping to monitor a cease-fire between Moroccan forces and the Polisario Front independence group. Longstanding efforts to find a political solution have been frustrated for years.

A United Nations spokesman, Farhan Haq, told reporters that the organization had received a message from Morocco asking the Minurso military liaison office in the coastal city of Dakhla be closed soon. He described the message as Morocco’s “first request targeting the military component” of Minurso.