There are 25 new cases of Covid-19 in New Zealand today, 23 are cases at the border and two are related to the port worker reported on Sunday.

Director-General of Health Dr Ashley Bloomfield says the two connected to the port worker are workplace contacts.

The first case was previously considered a casual contact of the port worker and had a very short exposure to the worker - about three minutes in the same room as them, says Dr Bloomfield.

"The new case became symptomatic yesterday, was tested yesterday and returned a positive result. They have one household contact who is now in self-isolation."

The second case is a previously reported close contact of the port worker. Dr Bloomfield says they were already at the Jet Park quarantine facility since Sunday. They were tested on Friday as part of the routine testing at the port and returned a negative test.

They developed symptoms yesterday, took a test and now returned a positive result, says Dr Bloomfield. "His household contacts were contacts of contacts but were isolated and tested anyway, they are now considered close contacts so will complete the full 14-day self-isolation."

"The ship the original positive case worked on in Auckland, that is now in Brisbane, is still is considered the most likely source of transmission. Tests have been taken but the results are not yet available."

There are 19 crew members on board the ship in Brisbane.

Moving onto the other cases in managed isolation, Dr Bloomfield says there are now a total of 18 cases in the Sudima Hotel in Christchurch that have Covid-19.

The chartered flight from Moscow that stopped over in Singapore carrying Russian and Ukrainian fishing crew members had tests undertaken before the flight took off. The testing, Dr Bloomfield understands, involved the nasal swab.

Dr Bloomfield says two people were not allowed on the flight because they tested positive.

A total of 235 fishing crew members are in the Sudima Hotel which is set up just for them.

Some of the 18 cases are new, according to the results of the tests, and some are probably historical, but ongoing testing continues, says Dr Bloomfield.

"The positive cases have now been moved into a dedicated quarantine wing within the Sudima Hotel."

Most of the people were in twin rooms, the close contacts of the 18 cases (those who were in the same room as the positive cases) are now in single rooms and the ministry is working to move all of the fishing crew into single rooms, says Dr Bloomfield.

"All of the staff working at the hotel have been tested over the last three days and additional testing will be provided."

Dr Bloomfield says people at the airport at Christchurch are being asked to be tested, as well as the bus company that transported the fishing crew to the Sudima Hotel.

On the remaining imported cases reported today - three unrelated cases arrived from London, via Singapore, on 16 October, they tested positive on routine day three testing at their managed isolation facility in Christchurch, says Dr Bloomfield.

He says there are also a further two imported cases at managed isolation facilities in Auckland - one arrived from Jordan via Dubai and Kuala Lumpur on 16 October and tested positive at routine day three testing.

The second person arrived from Malaysia on 17 October, they also tested positive on day three testing. Both are now on their way to the quarantine facility in Auckland, if they aren't there already, says Dr Bloomfield.

Two previously active cases are now considered recovered.

The total number of active cases is now 56 and the total number of confirmed cases in New Zealand is now 1556.

Yesterday the testing labs processed 6308 tests, the grand total is now 1,040,911.

Dr Bloomfield reiterated that if people are feeling sick they should get a test. People should also keep a record of where they have been, even if they are not feeling sick.

Answering questions, Dr Bloomfield says pre-departure testing would not make a difference to the protocols the ministry follows - it would still do its day three and day 12 testing when people are in managed isolation facilities.

He says the arrangement for the fishing crew coming into New Zealand was well planned by the fishing companies, the Ministry of Health and MPI and was signed off by ministers. He says the fishers were replacing New Zealand workers who have been at sea for an extended period of time - between six and 12 months - because of the Covid-19 pandemic.

Dr Bloomfield confirms another group of fishing crew is due to arrive in New Zealand in the next couple of weeks. He says this is not the first time a large group of essential workers has entered the country.

He says the ship anchored off the coast of Napier related to the original case confirmed on Sunday is still anchored offshore - the crew are symptom-free but are still considered close contacts. The crew are receiving daily symptom checks.

Yesterday the ministry confirmed that there were 11 cases of Covid-19 at a managed isolation facility in Christchurch, with another 14 possible cases being investigated.