"The trip to the Horn of Africa region over the Somalia arms embargo has been postponed," the official, who asked not to be named, told AFP by telephone, but declined to give reasons for the postponement or a date when the UN team is expected to travel to the region.
The team had been scheduled to visit Djibouti, Egypt, Eritrea, Ethiopia, Kenya and Yemen, as well as Somalia itself, depending on security there, from October 12 to 25.
The team was also to have looked into the ability of Somalia's neighbours to enforce a weapons embargo, first decreed by the UN Security Council in 1992 after two Somali warlords, Ali Mahdi Mohamed and the late General Mohamed Farah Aidid, agreed on a ceasefire in the divided Somali capital, Mogadishu.
But despite the embargo, weapons are still pouring into the war-torn Horn of Africa nation.
Rival warlords have accused Ethiopia, Eritrea, Yemen, Djibouti, Libya and Egypt of violating the embargo and arming rival factions, a charge that has been denied by the countries.
In April, the UN Security Council adopted a new resolution stating that Somalia constituted a threat for peace and safety in the region, and noted that the weapons embargo had been repeatedly violated.
Somalia has not had a recognised government and has been ruled by clan warlords since dictator Mohamed Siad Barre was overthrown in January 1991.