(CNN) Chinese personnel at the country's first overseas military base in Djibouti have been using lasers to interfere with US military aircraft at a nearby American base, activity that has resulted in injuries to US pilots and prompted the US to launch a formal diplomatic protest with Beijing, two military officials told CNN.

The US issued a notice to airmen "to exercise caution when flying in certain areas in Djibouti," which "was issued due to lasers being directed at US aircraft on a small number of separate occasions over the last few weeks," according to the notice obtained by CNN.

"During one incident, there were two minor eye injuries of aircrew flying in a C-130 that resulted from exposure to military-grade laser beams, which were reported to have originated from the nearby Chinese base," the notice said.

Two US military officials told CNN that the issue was of major concern as such activity can cause major accidents.

Military-grade laser beams, occasionally known as "dazzlers," omit a powerful beam of light that can travel great distances and be used to illuminate aircraft cockpits, temporarily blinding pilots.

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