Foreign Affairs Minister Murray McCully is expecting to receive updated information today about the death of Sarah Carter, one of seven who have died in mysterious circumstances in Thailand.

New Zealand officials in Thailand have been monitoring the investigation into Ms Carter's death but Mr McCully asked for a further briefing after it emerged Canadian Bill Mah, 59, died after using the facilities of the same hotel where Ms Carter, 23, fell fatally ill.

Ms Carter's father, Richard, contacted the Ministry of Foreign Affairs and Trade yesterday and asked them to start an independent investigation into the deaths.

"If the Thais are doing it themselves it's just likely to get glossed over," he said.

"Hopefully with all these deaths from all different countries, the various embassies will be able to put on enough pressure to get some sort of independent inquiry going."

When the sixth death was revealed this month, Mr Carter said he was not surprised and thought more would be uncovered.

Now he wants action to get answers.

"It's certainly at a stage now where they need to get cracking ... and my conversations with the friends of other deceased indicate that they have been frustrated in their attempts to find answers as well."

Ms Carter died in hospital from heart inflammation two days after she and two friends became sick while staying at the Downtown Inn in Chiang Mai.

An elderly British couple and a Thai tourist guide also died after staying at the hotel, and two other women died in Chiang Mai in similar circumstances within one month.

Thailand's Department for Disease Control said it could not find links between the deaths and authorities labelled them coincidental.

An initial report into Mr Mah's death on January 26 stated "suspected natural disease pending lab reports and toxicology" as the cause of death, but his friend said those results had still not been released.

Tests to determine the cause of Ms Carter's death are being carried out overseas, although the Herald understands an initial swab result indicated she had contracted echovirus.

The virus is linked to dirty conditions but Thai police gave the all-clear to the Downtown Inn, owned by a former mayor of the city, after checking it.

Mr Carter said he was searching for answers on behalf of visitors to Thailand.

"The grieving element will be hard to go away because of the fact we'll never get Sarah back. But the situation with following up on this is really more for the sake of future tourists, so the same situation doesn't happen to them."

He had tried to keep busy since his daughter's death but there were inevitably moments when the grief would catch up with him.

"When you're waking up to that as your first thought every day ... certainly the mornings and the weekends when we've got more time to ourselves seem to be the times when we're thinking a lot more of the tragic situation that befell Sarah."