BEIJING, May 24 (Xinhua) -- An official with the headquarters of China's Confucius Institute on Thursday said a U.S. government directive asking the institute's Chinese teachers on American campuses to leave may harm the Sino-U.S. friendship.

The official fake ray ban sunglasses, who preferred to remain anonymous, said the headquarters regrets the U.S. directive, and all of its centers around the world, including those on American campuses, were voluntarily requested by foreign partners, approved by the headquarters and jointly operated with Chinese colleges.

The Chinese teachers dispatched by the headquarters to the institutes were carefully selected and trained by both sides in an effort to help American elementary and secondary school students learn Mandarin and understand Chinese culture, the official said.

The directive sent by the U.S. Department of State on May 17 to universities which sponsor Confucius Institutes states that any academics at university-based institutes who are teaching at the elementary- and secondary-school levels are violating the terms of their visas and must leave at the end of the current school term in June.

It said that after a preliminary review, the State Department has determined that the institutes must obtain American accreditation in order to continue to accept foreign scholars and professors as teachers.

A report by the U.S. Chronicle of Higher Education said it is unclear what prompted the State Department to issue such a policy statement, as Confucius Institutes have been on American campuses for nearly a decade.

"If the teaching activities of the university-based Confucius Institutes were to be curtailed fake ray bans, that could have implications for U.S.-China relations," the report said.