The Ministry of Health has apologised after accidentally sending a text message to 6000 people telling them they have Covid-19 and need to isolate.

The message was sent to people who have tested positive for the virus in the last 10 days, meaning the text was a duplicate of advice they had already received.

The mistake was due to a computer glitch, the Ministry said.

An uploading error on Friday afternoon and through into Saturday morning meant people were sent repeat text messages mistakenly telling them they had returned a positive Covid-19 test.

"The duplicate text again told the recipient they'd tested positive for Covid-19 and gave the standard advice about isolating, asking them to fill in the contact tracing form and where to find information, support, and healthcare advice," the Ministry admitted tonight in a Twitter post.

The Ministry's contact tracing team discovered the glitch early on Saturday morning and the error was fixed that day.

Texts messages have been sent to all those affected to clarify the error, apologise and provide a phone number should people require further information or support, the Ministry said.

The phone line will be available this evening until 9pm and again from tomorrow morning.

The Ministry reported 4024 new community cases of Covid-19 in New Zealand today.

There were also a further nine Covid-related deaths.

The deaths include two people from the Auckland region, two from the Bay of Plenty, two from Wellington, two from Canterbury and one from South Canterbury.

One person was aged in their 40s, one was in their 60s, one was in their 70s, four were in their 80s and two were aged over 90. Of these people, six were women and three were men.

Today's reported deaths take the total number of publicly reported deaths with Covid to 1415.

There are 391 people in hospital with the virus, including three in intensive care.