U.S. military forces will stage maneuvers next month in Egypt, Jordan, Oman and Somalia, Defense Department officials said yesterday. It will be the first large-scale display of American military might in the region since the Beirut hostage crisis last month.

Pentagon spokesman Fred S. Hoffman said 9,000 U.S. servicemen will participate in the third major "Bright Star" military exercise with Egypt, a six-day maneuver scheduled to start Sunday.

The exercise will feature an amphibious landing on Egypt's Mediterranean coast, desert maneuvers and a simulated B52 bomber strike, he said.

A smaller "combined training" exercise in Jordan involving 520 U.S. troops will run until Aug. 17, said Hoffman, who declined to give further details about it.

Maneuvers in both Middle East nations, he said, are intended to provide "an opportunity for U.S. and other friendly forces to engage in combined land, naval and air training to enable each side to benefit from the other's expertise."

No counterterrorist exercises are planned, Hoffman said, despite Reagan administration warnings in the wake of the Beirut crisis that the United States will root out terrorists in the Middle East.

Hoffman said at least one other country in the region will participate in joint maneuvers with U.S. troops next month under the code name Bright Star. He would not identify which country or countries will be involved.

A military source said the Pentagon will announce Somalia's participation today. Somalia is considered the closest U.S. ally on the Horn of Africa, where Washington has tried to gain a military foothold to guard access to the volatile and oil-rich Persian Gulf.

Oman, the Persian Gulf sultanate, also will join U.S. troops in a small military exercise, but its participation will not be publicly disclosed because of Oman's fears of angering its Arab neighbors.

Washington has been engaged in delicate negotiations with Oman, which is seeking greater control over U.S. access to its strategically located airfields and other military facilities.

Oman's bases are considered extremely important for operations of the U.S. Central Command in a Persian Gulf military crisis.