The National War Memorial in Wellington has been closed indefinitely after engineers found it to be earthquake prone.

Photo: RNZ / Ana Tovey

The memorial reopened after a four-year closure in 2018, when its bell frame was refurbished and earthquake strengthening was completed.

Manatū Taonga - The Ministry of Culture and Heritage - said engineers completing that work suggested a detailed seismic assessment of the whole tower and the bell frames.

It has now received the report, which shows the Carillon tower is quake-prone.

The ministry closed the Carillon tower and Hall of Memories on Thursday last week, while it works through the assessment.

In a statement it said the Hall of Memories had already been earthquake strengthened but had to be closed as it was not possible to enter that section of the memorial without passing through the ground floor of the Carillon tower.

Brodie Stubbs, the Ministry's Te Pae Mahara manager, said an assessment showed potential risks with the bell frames of the tower, but said the tower is not at risk of collapsing.

He said that due to the potential risk to people inside the tower, the prudent thing to do was to close the building.

"The tower is a complex structure, probably unqiue within New Zealand," he said.

It is not clear when the memorial will re-open.

In the meantime, the Pukeahu National War Memorial Park and the Pukeahu education centre will remain open.