National says the Government needs to front over concerns about a new strain of Covid-19 in the UK, thought to be up to 70 per cent more contagious.
More than 40 countries have barred UK arrivals due to the new variant of coronavirus there.
As of today, Britain has detected another variant in contacts of cases who have travelled from South Africa.
Public health experts, including professors Nick Wilson and Michael Baker, have called for more stringent border measures in response.
The Government has declined several requests from RNZ for an interview this week.
In a statement, a spokesperson said they were in communication with health authorities in the UK and "monitoring the situation closely".
"The Ministry of Health is confident New Zealand's current use of PPE, testing strategy and 14-day managed isolation for all arrivals is appropriate. The ministry continues to review these tools in light of any new and emerging evidence.
"The Ministry of Health has always consistently said that our most important protection at the border is the 14 days in isolation and/or quarantine, together with the daily symptom checks [and testing if symptomatic].
"We are also confident our current PCR testing would detect this and any new strains," the statement said.
But National's Covid-19 Response spokesman Chris Bishop said at a time of heightened public concern, that was not good enough.
"Christmas is a time for relaxation and holiday, but it's also a time at which we must not become complacent, because there'll be people coming into New Zealand every day, we do need to make absolutely sure our border is secure.
"People want to know that the border's secure not just in the days leading up to Christmas but actually over the Christmas break as well, so I would expect some more answers from the government in the coming days," he said.
Bishop said the Government needed to respond to the new strain by introducing pre-departure tests for arrivals from the UK.
"No one is saying that it's a silver bullet, it's not something that's going to magically eliminate Covid overnight, but we think it's an important part of a suite of tools that can be used to make sure our border response is as top notch as possible."
Bishop said the situation in the UK was another example of why the Government should introduce a "traffic light system" to grade the risk of incoming travellers.
"That would allow a much more intensive regime for people coming from the UK, for example, compared to people from Australia. That's what people like Professor Baker and others have been calling for, and I think it's really now time to look at implementing that."