A US navy fighter jet crashed in the Persian Gulf as a helicopter went missing in Nepal.

A US navy fighter jet crashed in the Persian Gulf shortly after taking off from the aircraft carrier USS Theodore Roosevelt Tuesday, the Navy said in a release.

Both crewmembers survived, the release issued by Fifth Fleet said, adding that the crash was not a result of hostile activity.

The two personnel from Strike Fighter Squadron 211ejected and were quickly recovered by search and rescue personnel from the ship, said the Fifth Fleet, which is responsible for the area where the Roosevelt is deployed, conducting air strikes against ISIL Takfiri group in Iraq and Syria.

Meanwhile, a US Marine Corps helicopter carrying out earthquake relief in Nepal was reported missing on Tuesday with eight personnel on board, officials said.

"The incident occurred near Charikot, Nepal while the aircraft was conducting humanitarian assistance and disaster relief operations," said Major Dave Eastburn, spokesman for US Pacific Command.

The UH-1Y Huey, which was carrying tarps and rice, had just dropped off supplies and was headed to another destination, officials said.

Before the chopper went missing, there was "some chatter about a fuel problem" on the radio from the helicopter crew, Pentagon spokesman Colonel Steven Warren said.

The chopper was carrying six US Marines and two soldiers from the Nepalese army, officials said.

The Huey helicopter was last seen west of Charikot but a search of the area was unsuccessful.

A search by aircraft before nightfall had not spotted any sign of smoke or any crash site, raising hopes the helicopter may have made a safe emergency landing, he said.

The Nepalese army was conducting a search on the ground but aircraft could not fly until daylight to resume the search from the air.