At least 11 Chinese construction workers have been killed in Afghanistan in an attack described by Beijing as a "brutal terrorist act".
Kunduz, where German troops are based, was seen as a safe area
An Afghan national was also killed and several Chinese wounded.
The attack took place in north-eastern Afghanistan, an area considered one of the safest in the country.
No one has claimed responsibility for the incident. It is the second fatal attack on foreign workers in Afghanistan in a week.
The BBC's Charles Haviland in Kabul says there are increasing fears that a mounting insurgency by suspected Taleban and al-Qaeda fighters in the south-east of the country is spreading.
A senior source at the interior ministry in Kabul told the BBC that the killings took place when about 20 armed men attacked two tents in which the construction workers were sleeping, south of the city of Kunduz.
"They died in their beds, most of them with stomach and head wounds," Kunduz police chief Mutaleb Beg told the Associated Press news agency.
Chinese officials say the dead men were part of a team of 100 Chinese nationals employed by the China Railway Construction Shisiju Group Corporation.
The men - most of whom came from the eastern Chinese province of Shandong - were employed building a road in the region.
The attack occurred at 0100 (2030GMT Wednesday). Reports say the attackers first killed an Afghan guard before shooting the Chinese.
The local military commander, General Mohammed Daud said the attack was the work of "the enemies of Afghanistan - the Taleban and al-Qaeda," the AFP news agency reports.
A Chinese foreign ministry spokesman said President Hu Jintao had condemned the "inhumane, brutal attack".
China's ambassador to Kabul, Sun Yuxi, was reported to be on his way to the scene.
Many of the victims had barely been in Afghanistan for a week.
The motive behind the attack - one of the bloodiest yet on foreigners in Afghanistan - is not clear.
However, recent months have seen a steady rise in the targeting of foreigners by members of the deposed Taleban regime.
Last week, three Europeans and two Afghans working for the Medecins sans Frontieres aid agency were ambushed and killed by gunmen in north-western Afghanistan, an area that was broadly regarded as safe from extremists.
According to China's official Xinhua news agency, Chinese firms are involved in three major projects in Afghanistan - renovating a hospital in Kabul, rebuilding major road links and repairing Parwan's irrigation canals.
China reopened its embassy in Kabul in 2002, after an interval of almost a decade during the heavy fighting between the Taleban and other factions.
Northern Afghanistan is seen as one of the most stable areas of the country with about 200 German peacekeepers based in Kunduz.
Attacks on Chinese abroad are rare, but last month a car bomb exploded in the Pakistani city of Gwadar, killing three Chinese engineers who were working on a project to expand port facilities.
Pakistani President Pervez Musharraf described that attack as a "barbaric act of terrorism".