HONOLULU: High waves for the next several days will hamper the search for 12 Marines missing at sea after two helicopters collided near the island of Oahu in Hawaii, US Coast Guard officials said on Friday.

Two Coast Guard cutters and several Coast Guard aircraft were searching, along with two US Navy warships and local police and fire department helicopters, the Coast Guard said.

A safety zone has been set up from the shoreline that matches up with the accident site to 13 km out to sea, the Coast Guard said.

“We’ve seen debris through the entire area,” said Lt. Scott Carr, a Coast Guard spokesman. He added the high surf was expected to last until at least Tuesday.

The CH-53E helicopters, belonging to the 1st Marine Aircraft Wing from the Marine Corps Air Station at Kaneohe Bay, were reported to have collided just before midnight local time (1000 GMT), Coast Guard spokeswoman Sara Mooers said.

The wide-ranging search for the Marines was hampered by high surf and poor visibility from rain storms. The National Weather Service warned that a northwest swell would bring 35 foot to 45 foot (11 meter to 14 meter) surf to the area through Friday.