China has dispatched a working group to Vietnam after at least 21 people were killed in rioting, the country's official news agency has said.

Xinhua reported on Thursday evening that the team, led by Assistant Foreign Minister Liu Jianchao, would deal with the aftermath of Wednesday's violence that saw people burning and looting foreign-owned factories in Vietnam. There has also been unrest in the capital, Hanoi.

China's foreign minister has said Vietnam "bears unshirkable responsibility" for violence directed towards Chinese companies and nationals.

Xinhua reported that Foreign Minister Wang Yi called Vietnamese Deputy Prime Minister and Minister of Foreign Affairs Pham Binh Minh on Thursday evening.

During the call, Pham was reported as saying that Vietnam authorities had apprehended more than 1,000 suspects and would "severely punish" the lawbreakers.

"The Vietnam authorities will also take measures to protect the safety of the lives and property of all Chinese nationals and organizations there," the news agency added.

Concerns over China's aggressive behaviour in the South China Sea dominated a regional summit hosted in Myanmar earlier this month.

Source: Al Jazeera and agencies