A ministerial promise that high-risk 5G network suppliers such as Huawei would eventually be phased out of future UK phone networks has failed to quell a brewing Conservative revolt over the issue.

Rebel backbenchers said the clarification made by Matt Warman, a junior minister, at a Westminster Hall debate was not enough because he would not commit to a timetable to eliminate the Chinese supplier, which they claim is a national security risk.

Warman told MPs in a special debate about Huawei: “We want to get to a position where we do have not to use a high-risk vendor in the network at all.”

Iain Duncan Smith, a former party leader, intervened to ask Warman whether it was now “government policy to drive to 0% involvement by Huawei and other non-secure vendors” – the key demand from the 30-strong rebel group.

Warman said he could not go any further to satisfy critics. “I appreciate that he would like me to set out a timetable and I can’t do that today,” the minister said.

Another former minister, Owen Paterson, said Warman’s clarification was not enough. “He’s so nearly got the government to the right position,” Paterson said at the end of the debate. “He’s admitted that Huawei is high-risk. He’s admitted it’s the government intention to get to no high-risk vendors. He’s admitted he listens to our allies. They’re overwhelmingly against this. Australia, France, United States all said they have taken advice.”

Rebel sources said after the meeting that while they thought Warman was well-intentioned, he had struggled to defend the Huawei policy and they would continue their campaign when the measure is put to a Commons vote.

Last month Boris Johnson’s government announced plans to cap Huawei’s market share in 5G at 35%, despite intense pressure from Donald Trump, to eliminate the Chinese company’s involvement entirely.

The White House and the Conservative rebels believe Huawei technology represents a potential surveillance risk, but Downing Street and Britain’s spy agencies believe any risks can be managed.

Huawei is already a leading supplier of 3G and 4G technology, present particularly in the BT-owned EE network and Vodafone, and the government says the lack of diversity in the wider market makes it practically impossible to eliminate 5G in the short or medium term.

Phone companies will have to make reductions in the amount of Huawei kit deployed in order to meet the 35% cap, officials have indicated.