China has urged the US to condemn what it says are “terror attacks” in Xinjiang that killed 21 people, the deadliest violence in the ethnically-divided region.

Authorities in Beijing called the violence “terrorism” after 21 people, including members of Uighur ethnic minority, were killed in the clashes, which escalated into a knife, axe and arson attack, according to Reuters. Six Uighurs were suspected of “terrorist plotting,” local officials said.

Global Times quoted Xinjiang spokeswoman Hou Hanmin as comparing the attacks to the recent Boston Marathon bombings, which the US described as an “act of terrorism”.

The US State Department, however, merely expressed regret over the deaths in a backhanded swipe at the country’s human rights issues, particularly its alleged persecution of minority Muslim Uighurs.

Washington then urged China to “provide all Chinese citizens, including Uighurs, the due process protections to which they’re entitled”.

Chinese foreign ministry spokeswoman Hua Chunying accused the US of having “double standards” for refusing to condemn the attack.

“We simply oppose the US reversing black and white, confusing right and wrong, and continually refusing to condemn violent terrorist incidents, and instead, making wild accusations about Chinese policy toward ethnic minorities,” she said.