WASHINGTON • The US formally complained to China after Chinese nationals pointed lasers at US military aircraft near Djibouti in a number of incidents in recent weeks, the Pentagon said, an account disputed by China.

The United States military has been grappling with lasers being pointed at aircraft for decades. However, the incidents highlight the concern the US has about a Chinese military base just kilometres from a critical US base in the east African country.

"They are very serious incidents... We have formally demarched the Chinese government and we've requested the Chinese investigate these incidents," Pentagon spokesman Dana White told reporters on Thursday.

Ms White said the Pentagon was confident that the lasers had been pointed by Chinese nationals and in the past few weeks fewer than 10 incidents had taken place. The intent was unclear.

A US official, speaking on condition of anonymity, said that in one incident last month two pilots in a C-130 suffered minor eye injuries.

The official said in a few cases, military grade lasers from the Chinese base were pointed at aircraft. China's Defence Ministry did not respond to a request for comment.

But Foreign Ministry spokeswoman Hua Chunying disputed the US accusations.

"I can tell you the Chinese side, having conducted serious checks, has already clearly told the US side that their so-called criticisms totally do not accord with the facts," she told a daily briefing in Beijing.

Djibouti is strategically located at the southern entrance to the Red Sea on the route to the Suez Canal.

It hosts a US military base that is home to about 4,000 personnel, including special operations forces, and is a launch pad for operations in Yemen and Somalia.

REUTERS