There are 31 new cases of Covid-19 in managed isolation since Thursday.
There are no new cases in the community. Nineteen cases at the border are now linked to the rapidly-spreading UK strain of coronavirus.
"The number of cases reinforces the need for ongoing vigilance at the border, as Covid-19 continues to accelerate overseas," the Ministry of Health said.
There are 11 new cases linked to a group of international mariners.
"Only three of these cases have been identified as current cases, while the majority (eight) have been identified as historical cases. A total of 190 mariners arrived on Wednesday and are staying at managed isolation and quarantine facilities in Christchurch," the ministry said.
"A number of mariners were not able to board flights to New Zealand after testing positive during pre-departure testing.
The managed isolation and quarantine facilities have strengthened procedures and protocols to ensure the risk to others in the group and in the facilities is reduced."
The ministry said there are 19 cases in total - in people in managed isolation facilities - which are linked to the rapidly spreading UK coronavirus strain. One case is linked to the South African strain, the ministry said.
"Most of these people have come into New Zealand from the UK, via the UAE, Qatar or Singapore," the ministry said.
The new strain has forced the UK back into lockdown, amid fears its health system will become overwhelmed.
On Saturday, the British government reported the number of confirmed deaths had reached 80,868 - the highest in Europe and the world's fifth-highest pandemic death toll. A day earlier, the country's daily reported deaths had hit a record high of 1325.
The new and more contagious UK variant can be passed on easier than other strains of the virus.
However, there was no evidence at this stage that the length of the infection period was any different to any other variant of Covid-19 or that it made people sicker, a ministry statement said.
The ministry said people who had tested positive for the new strain were being cared for with the same high level of infection prevention measures as all Covid-19 cases.
"Infection prevention control protocols are in place for all staff and we can assure the public that there is no increased risk to the community," the statement said.
Hamilton District Court was placed into a short lockdown on Wednesday after a woman who worked at a managed isolation facility turned up at court and told a staff member she had a runny nose and was awaiting the result of a Covid-19 test.
The lockdown was lifted after about an hour and a half, and about 40 to 50 members of the public were allowed out, but the court remained closed for the rest of the day.