A mummified head said to be that of a South Sea island chief is to be sent back to New Zealand after more than 150 years in the UK.

The Maori head, or toi moko, was brought to Britain in the 1840s and kept at Warrington Museum in Cheshire.

The museum announced it was sending the head back to its motherland due to its "great cultural importance".

Janice Hayes, the museum's manager, said: "We don't know the precise origin of the head. We do know that the Maoris used to preserve severed heads for two reasons – either to venerate a loved one, or to ridicule an enemy defeated in battle.

"But we also know that some Maoris, when they learned that Europeans would pay gold for the old artefacts, began to manufacture more heads for sale."

She said Te Papa Tongarewa, the museum of New Zealand, had been asking for all such artefacts to be repatriated, at their expense, and Warrington borough council, which legally owns the head, had decided to return it.

"In Maori culture the head is considered to be the most sacred part of the body and male warriors would have an intricate facial tattoo called a moko applied to give it additional sacred powers," she said.

"After their death their head was smoked and dried in the sun to preserve it and ensure it was still possible to see their unique moko which allowed them to be identified, almost like a finger print.

"Because these toi moko are so sacred to the Maori it is regarded as an insult even to show a photograph of one and the museum removed the head from public view many years ago."

The council's executive board member for leisure, community and culture, Kate Hannon, said: "We're proud to have had this toi moko in Warrington Museum for all this time, and there's a lot that can be learned from artefacts like this.

"But we think it's right and proper that the head should be returned to New Zealand.

"Human remains like this are of great cultural importance to the Maoris, and we're very happy to see to it that the toi moko is returned to where it came from a century and a half ago."

Te Papa Tongarewa has indicated that it will want to conduct a ceremony at Warrington Museum to thank it for its care of the toi moko before the New Zealand authorities resume custody of it.

The artefact is unlikely to be repatriated until the autumn so Warrington borough council intends to invite members of the New Zealand and Samoan national rugby league team to pay their respects to the toi moko during their stay in the UK as part of the World Cup.

• This article was amended on 7 August 2013. A photo of a plaster cast copy of the toi moko was removed out of respect for the sacredness of the Maori head. An indirect quote stating that many Samoans were of Maori origin was also removed.