A young Hawke's Bay Metallica fan has received a letter from the Prime Minister congratulating him on his efforts to bring the band to New Zealand.

Twelve-year-old William Bush launched a petition in September to bring the maestros of heavy metal to our shores, which had clocked up more than 4000 signatures at 3:30pm on Saturday.

Bush, who attends Havelock North Intermediate, said he was surprised to find the letter from Jacinda Ardern in his mailbox on Monday.

SUPPLIED William Bush, 12, who petitioned Metallica to perform in New Zealand.

"It's not often the Prime Minister sends you a letter."

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In the letter, Ardern says: "It's great to hear about young New Zealanders who are passionate about music.

"I grew up listening to Metallica and I'm really impressed by all the effort you have put into getting them to play a show in New Zealand."

She ends by wishing him well with his campaign, adding "I hope you get to see Metallica play soon!".

Bush's hopes that Metallica will add New Zealand to their WorldWired tour were boosted after stand-up comedian and actor Jim Breuer, who opens for the American band at their shows, shared his post about the petition on social media.

"I'm pretty hopeful," he said.

Bush said he grew up listening to the sorts of radio stations that play Metallica's music.

"They're one of my favourite bands and they haven't played in New Zealand since 2010," he told Stuff in October. "I was four in 2010. So I thought, what other way to get them to play here than to start a petition?"

Bush said it is not the first time a petition has tried to lure the band to New Zealand.

MICHAEL CAMPANELLA James Hetfield of Metallica performs during their WorldWired tour.

"In 2010 someone started a petition to get Metallica to play here, in Christchurch. They got 20,000 signatures, and that attracted the attention of the band and got them to play here. We're aiming at about 10,000-20,000."

Bush has had success with his online campaigns in the past.

Last year, he launched an appeal to get Frankie MacDonald, a then-33-year-old YouTuber from Nova Scotia, on the Ellen DeGeneres Show - a lifelong dream.

Bush, who plays guitar, said he does not "necessarily" have a favourite Metallica song.

In September, the band sparked rumours they were planning a visit to the Antipodes in the near future.

MICHAEL CAMPANELLA James Hetfield of Metallica performs during their WorldWired tour.

In an interview with their fan magazine So What!, drummer Lars Ulrich name-dropped New Zealand as a destination the band hadn't visited for some years.

"We gotta just sit and look. There's Japan. There's Australia. There's New Zealand. There's a couple other pockets that obviously Metallica has a long and very cool relationship with, so we just gotta sit down and figure it out."

Sign William's petition here or via his Facebook site.