The government is checking whether New Zealand has an exemption from immigration curbs in the US, Prime Minister Bill English says.

Watch Bill English on Morning Report

Donald Trump has halted the US refugee programme for 120 days, indefinitely banned all Syrian refugees and suspended for 90 days the entry of all nationals from seven Muslim-majority countries. This would involve people with dual nationalities.

There have been reports that some countries have exemptions for their passport-holders who are from the seven Muslim-majority countries.

"I see there's stories that the Canadians do, that the Australians are seeking it," Mr English said.

"The impression I get is that this policy is unclear but we will be checking up on that.

"It's our expectation that if someone is travelling on a New Zealand passport then they have that exemption."

British Foreign Secretary Boris Johnson has said the crackdown will make "no difference" to anyone with a British passport. He said he had been assured Britons born overseas or with dual passports would not be affected.

Mr English said he would be seeking exemptions for New Zealand but he had not yet received any assurances from the US.

"As far as I'm aware there's no Kiwis, no-one with a Kiwi passport, caught up in this change of policy but we will have to check up on what the formal policy position is."

Mr English said yesterday he disagreed the immigration curb and New Zealand would not implement that type of policy.

He said the 90-day ban had caused "some real chaos" in the short term but "we have yet to see what turns out to the the long term policy".

Asked whether the US policy was racist, he said he did not believe it was. "But I'm not here to defend the policy," he said.

"It discriminates among them [refugees] by which country they come from.

"I'm not trying to defend or explain the policy. That is the job of the American government."

Muslim New Zealanders would make up their own mind about the policy, and he was stating that it was not going to be implemented in this country, he said.

- RNZ / BBC