A faction of the Pakistani Taliban claimed responsibility on Thursday for the killing of a Chinese woman this week, saying it was in revenge for China's killing of Muslims in its troubled northwestern region of Xinjiang.

The claim of responsibility is likely to alarm both the Pakistani government and China, which is a close ally of Pakistan and has considerable investment in its south Asian neighbour.

The Chinese woman was shot on Tuesday in a market in the northwestern city of Peshawar along with a Pakistani man. Police at the time said they did not know the motive.

Our comrades carried out the attack in Peshawar which killed the Chinese tourist, Mohammed Afridi, a spokesman for a faction of the Pakistani Taliban from the Darra Adam Khel area, told Reuters by telephone from an undisclosed location.

This was revenge for the Chinese government killing our Muslim brothers in their Xinjiang province.

Pakistani and Chinese officials have said that Islamist militants based in western China have links to the Pakistani Taliban and other militants in northwestern Pakistani regions along the Afghan border.

China accuses one group, the East Turkestan Islamic Movement, of carrying out attacks in China and says it has broken up training camps for men seeking independence for China's the largely Muslim Xinjiang region.

The Pakistani Taliban, an umbrella organisation of militant factions, is battling the Pakistani government. It has also attacked foreigners from countries and organisations backing the government.

Afridi said the militants were also demanding that China halt what he called its support for the Pakistani government's campaign against militants, and said attacks would go on against Chinese people as long as China maintained that support.

There have been several attacks on Chinese people in Pakistan over the past decade by Islamist militants and autonomy-seeking rebels in the southwestern province of Baluchistan.

China, while calling on Pakistan to ensure the safety of its citizens, has maintained close economic and diplomatic ties. The Chinese embassy in Islamabad called for action after the latest incident.

The embassy has requested the Pakistani side to conduct a thorough and immediate investigation, bring the murderer to justice and properly deal with its aftermath, it said.

The Pakistani side is also requested to take effective steps to ensure the security of the Chinese nationals in the country.

Pakistan's ambassador to China, Masood Khan, vowed that the attackers would be tracked down.

China has been Pakistan's most steadfast ally for decades, providing diplomatic and military support and investing in a range of sectors including infrastructure and nuclear energy.