Arriving from Beijing last week, Celeste Zhang claimed airport authorities separated her and a female travel companion and questioned them for about half an hour about their reasons for coming.

Miss Zhang, 23, a nursing graduate, and her friend, who did not want to be named, said they were offended that immigration officials at the airport had suggested they could be here to look for work in the sex industry.

Figures released by Statistics New Zealand yesterday showed a boom in tourists from China helped boost visitor numbers to New Zealand by 11 per cent in March compared with the same month last year. Visitors from China were up 8700, the second highest monthly increase for tourists from that country.

Auckland-based Chinese tour operator Chris Li said single Chinese women were often held up at the airport and viewed suspiciously when they arrived here. He said they often took about 45 minutes longer to be processed.

However, Immigration NZ said it did not treat incoming single Chinese female travellers differently.

Last year, 664 people were refused entry at the airport, including 21 Chinese, of whom just seven were women.

Reasons for refusing entry included non-genuine reasons for travelling, visa problems and if the traveller was thought to be likely to commit a crime.

Tourist numbers from Australia also rose in March, up 8400, because of an earlier Easter and Australian school holidays.

In the year to March, 2.618 million visitors came here, up 4 per cent from 2011.

The largest rises were for visitors from China, Australia, Malaysia and Japan. Overseas trips taken by New Zealanders were also up 7 per cent at 153,000.

MARCH FOREIGN ARRIVALS

* China 19,200 (up 8700)
* Australia 102,016 (up 8400)
* Malaysia 3728 (up 1600)
* Japan 8208 (up 1400)
* Total: 239,929 (up 24,376)
Source: Statistics New Zealand.