The Afghan envoy to China has questioned the Taliban’s assurance to Beijing that they will not harbour Islamist terrorists trying to divide Xinjiang, saying the rebel organisation cannot be trusted to follow its word.

“I don’t think even China believes in that (the promise),” Javid Ahmad Qaem told Reuters in an interview in Beijing, adding that the Taliban were “only saying this to get regional support”.

Qaem’s statement comes a week after China, led by state councillor and foreign minister, Wang Yi hosted a Taliban delegation in the northern city of Tianjin, close to Beijing.

Wang urged the Taliban delegation led by Abdul Ghani Baradar, the Taliban’s political chief, to crack down on the East Turkestan Islamic Movement (ETIM), an Islamic group it alleges is fuelling unrest and separatism in China’s Xinjiang province from Afghanistan.

Tweeting about the talks, Taliban spokesperson Mohammed Naeem said: “(The) delegation assured China that they will not allow anyone to use Afghan soil against China.”

Qaem wasn’t convinced, saying it was unlikely that the Taliban would turn against the ETIM. “It’s the same ideology. How could you expect somebody with the same thinking to fight other people who are with the same thinking?” he said.

In the readout issued by the Chinese government after the talks with Taliban, Wang called them a “significant military and political force” expected to play a key role in Afghanistan’s reconstruction.

Qaem told Reuters that he would prefer that China was fully behind the Afghan government but also said that Beijing was transparent about its engagement with the Taliban, informing Afghanistan before extending its invitation and briefing it afterwards. “We have faith in the Chinese intentions.”

Qaem said China could ask Pakistan to build trust with the Afghan government, given that Islamabad has long seen the Taliban as the best option for limiting the influence of India in Afghanistan.

China could also serve as a conduit for messages from Kabul to the Taliban, as it was at last week’s meeting – relaying a government call for a ceasefire and an appeal for an inclusive political framework, he said.

China can also help in boosting trade and buying more Afghan products such as saffron, he said. “So as long as that is provided, I don’t think China needs to send boots.”