WELLINGTON : Prince William proved his star power on Monday as thousands of New Zealanders cheered the second-in-line to the throne in the face of a small republican demonstration.

The 27-year-old prince opened a new Supreme Court Building in Wellington during the second day of his first official trip overseas on behalf of his grandmother, Queen Elizabeth II.

The prince was loudly cheered as he arrived to be draped in a ceremonial Maori feather cloak and received a haka, or challenge, from a group of bare-chested warriors in grass-skirts.

A group of distinguished Maori elders met William with a hongi, touching noses in a Maori greeting.

"We love you William," one woman called out from the crowd.

The number of spectators swelled to between 3,000 to 4,000 as the 27-year-old prince left the building after the hour-long opening ceremony and walked among the crowd, shaking hands and greeting enthusiastic onlookers.

"Have you been waiting all this time? I'm so sorry," he told one woman.

The largest group of protesters, representing justice ministry staff demanding more pay, fell quiet as the prince approached, pressing to shake his hand and take photos.

Draped in a New Zealand flag, onlooker Sue Reid said William was a good example for young people, including daughter Zara, seven, who was by her side.

"I like the fact he is a good role model for my children. He's kind and compassionate, not like some of these rock stars," Reid said.

Reid's mother Jan Howie, from Tasmania in Australia, was draped in the Australian flag and added approvingly that William supported good causes, like his late mother Princess Diana.

"You look just like your mother," another woman called out to the prince.

William was smiley and chatty in the half hour he spent moving around the low barricades separating him from the crowd, as a group of about 20 security staff kept a close watch.

There was no sign of the shyness evident in William's youth, although his face did start to redden in the bright summer sunshine.

A group of excited teenage girls compared notes after shaking the prince's hand.

"He has a really confident handshake, no clamminess," one said.

Asked why they wanted to meet him, a couple chorused: "He's not married".

"I didn't get a chance to say anything to him, I think I was star-struck," another added.

Polls show more than 40 percent of New Zealanders support New Zealand eventually becoming a republic.

But there was little support in the Wellington crowd for a small band of noisy protesters who unfurled a banner reading: "It's time for a republic".

"Prince William might be a nice guy, but it should be a New Zealander, chosen by New Zealanders, opening our highest court of appeal," the Republican Movement's chairman Lewis Holden said.

Prime Minister John Key, who accompanied the prince during the court opening, said the republican debate would be "no shocking revelation" to William.

"I personally don't think New Zealand is going to become a republic anytime real soon, but it's not something that they are afraid to debate as royals," Key told commercial radio.

The prince was due to visit an offshore island wildlife sanctuary later Monday before attending a barbecue at Key's official residence in Wellington.

He was to visit children at Wellington Hospital on Tuesday morning before flying to Sydney for a three-day unofficial visit to Australia.