The former Soviet republic shares a lengthy mountainous border with Afghanistan and has tense relations with the Taliban.

Several border attacks by local gangs have broken out in recent months despite increased communication between regional officials from the two countries.

On Sunday, "two citizens of the People's Republic of China were killed, two more citizens of this country were injured," the Tajik border guard said on Monday, adding that "members of an armed terrorist group" had attacked workers of a Chinese road construction company.

A drone launched from Afghanistan also killed three Chinese workers last week, according to Tajik authorities.

The Tajik border guard called on "the current authorities of Afghanistan to take timely and effective measures to ensure security" in the border region and to arrest the perpetrators.

The Chinese embassy in Tajikistan told its nationals to "urgently evacuate the Tajikistan-Afghan border area", while calling on Dushanbe to ensure the safety of its citizens.

Tajik President Emomali Rakhmon "strongly condemned the illegal and provocative acts of Afghan citizens" in a statement on Monday, ordering his border guard to beef up security in the region.

The Afghan government said last week it was open to cooperation with Tajikistan on investigating the incidents.

Several Chinese companies operate in Tajikistan, mostly in mining and natural resources, often located in the mountainous border areas.

They also build roads as part of Beijing's ambitious infrastructure projects.

Muslim-majority Tajikistan, one of the poorest countries in the former Soviet Union, has been concerned about possible flare-ups in extremism since the Taliban returned to power in 2021.

Rakhmon, in power since 1992, is openly critical of the Taliban, and urged the group to respect the rights of ethnic Tajiks, estimated to make up around a quarter of Afghanistan's 40-million population.