WELLINGTON - Three New Zealand Red Cross healthcare workers have been cleared of possible Ebola infection after being put on "self-monitoring" since returning from working in Ebola-affected countries in West Africa, Health Minister Jonathan Coleman said Tuesday.

Seventy-four people had been "flagged" since border screening for Ebola was introduced in New Zealand on Aug 10, Coleman said in a statement.

A traveller was flagged if they had been in an Ebola affected country within the last 30 days.

"Of those 74 people, three had been pre-identified and put onto self-monitoring for the length of the Ebola virus incubation, which is 21 days from their last potential exposure. All three have now been cleared," he said.

"Self-monitoring for Ebola involves a person taking their temperature twice a day, and daily catch-ups with a public health officer," he said.

"It is important to note that people infected with Ebola are not infectious before symptoms develop."

Health and border authorities were well prepared to detect and respond to any potential cases of Ebola.

"While the risk to New Zealand remains low, we cannot guarantee that we won't get a case here," said Coleman.

Prime Minister John Key said earlier Tuesday that New Zealand would continue with voluntary reporting on Ebola for the time being and would not be following Australia's lead on stronger new border and quarantine measures, Radio New Zealand reported.

The government relied on people to voluntarily present themselves to immigration authorities if they believed they had been exposed to Ebola, and it saw no need for a tougher regime, Key said.

Only about one person a day arrived from countries that might have been affected, and the current system was adequate, Key said in the report.

Australia has moved to stop processing humanitarian and immigration visas from affected West African nations.

All non-permanent or temporary visas are being cancelled and permanent visa holders who have not yet arrived in Australia will be required to submit to a 21-day quarantine period.