Britain has emerged as a key battleground in a geopolitical battle over Huawei Technologies, the world's biggest maker of telecom networking equipment.
The United States has threatened to cut off valuable intelligence sharing with allies who use the company's equipment, which it says could be exploited by Beijing for spying. China has warned Britain that excluding the firm could hurt investment and trade.
Britain's National Security Council, chaired by outgoing Prime Minister Theresa May, met to discuss the issue in April and a decision was made to block Huawei from all critical parts of the 5G network but to give it restricted access to less sensitive parts.
The final decision on Huawei was already supposed to have been taken by the British government but May's decision to step down has stalled the process. Her replacement, either foreign minister Jeremy Hunt or former London mayor Boris Johnson who is the frontrunner, will be installed next week.
"Such an important decision therefore requires careful consideration," parliament's Intelligence and Security Committee (ISC) said in a statement. "However, the extent of the delay is now causing serious damage to our international relationships: a decision must be made as a matter of urgency."
The ISC said Britain's cyber security chiefs had been clear that the issue was not about one country or company, but that the national networks had to be able to withstand any attack, malicious action or simple human error.
The committee said this was best achieved by diversifying suppliers and the issue at the moment for 5G was that there were only three firms in the running - Huawei, Nokia and Ericsson. Overdependence and less competition resulted in lower security standards, it said.
"Therefore including a third company - even if you may have some security concerns about them and will have to set a higher bar for security measures within the system - will, counter-intuitively, result in higher overall security," the ISC said.
Huawei Vice President Victor Zhang said he supported the committee's comments on supplier diversity. "We agree that diversity improves resilience in networks," he said.
The ISC also acknowledged, however, that the decision was not just technical and that the government had to take into account political concerns and so should not do anything to jeopardise the "Five Eyes" intelligence alliance of the United States, Britain, Australia, Canada and New Zealand.
It argued that China would understand if Huawei were excluded as Beijing would not allow a British company to play a role in its critical national infrastructure.
"The public debate implies that we have to choose between good economic links with China and our own national security ... This is a simplistic viewpoint, and those promoting it do a disservice to China," it said.