In a remote pocket of Tasmanian wilderness, the giant tree known as Centurion can now rightfully claim to be 100 metres tall.

Discovered a decade ago, the Eucalyptus regnans tree hadn't quite reached the mark when it was first measured at 99.7 metres.

But state-of-the-art laser technology used last month confirmed Centurion had grown to 100.5 metres.

While it was already home to the tallest flowering plant in the world, Tasmania now joins northern California in holding the only trees more than 100 metres in height.

Centurion also holds the title of tallest hardwood tree in the world.

Growth spurt

Yoav Daniel Bar-Ness from Giant Tree Expeditions said it was an exciting milestone.

"It looks like in the last three years it's cracked the 100-metre mark," he told Helen Shield on ABC Radio Hobart.

Centurion has grown in recent years to reach 100.5 metres in height. ( Supplied: The Tree Projects )

Mr Bar-Ness and Steven Pearce, from the The Tree Projects, said the laser range finder they used was accurate to within four centimetres.

"It's a really fancy tool that does a lot of trigonometry in the machine," Mr Bar-Ness said.

"We found a few points where we could see known landmarks on the stem of the tree and got the heights for those."

Tall trees protected

Centurion sits in forest near the Tahune Airwalk tourist attraction in the state's south, on land managed by state-owned logging company Sustainable Timber Tasmania (STT).

It was discovered in 2008 by STT staff who were mapping timber resources using aerial laser technology.

They gave it the name Centurion, not for its height but because it was the 100th giant tree to be registered.

Yoav Daniel Bar-Ness and Steve Pearce teamed up to get the latest measurements. ( Supplied: The Tree Projects )

A spokesman said the company welcomed the new measurement.

"In 2008 the tree was measured by tree climbers at 99.7 metres, by dropping a measuring tape from the top of the tree, one of the most accurate ways to measure really tall trees," he said.

Centurion is growing on public production forest managed for multiple uses by STT.

The spokesman said the area was set aside to "protect this magnificent forest giant and other forest values".

"In recognition of the natural and cultural significance of giant trees, Sustainable Timber Tasmania has a policy to protect all trees 85 metres or taller, as well as the very large fat trees with stem volumes greater than 280 cubic metres."

Most of Tasmania's recorded giant trees are in world heritage areas, national parks and other conservation reserves.

Centurion was measured using laser technology. ( Supplied: The Tree Projects )

Forest giants rare

Mr Bar-Ness said it was unlikely there were more trees in the Tasmanian wilderness taller than 100 metres.

"There used to be quite a few trees that were much taller," he said, adding that Centurion had signs of a broken stem high in its foliage, indicating it used to be taller.

"Ultimately it's not about how tall the tree is, it's about how old and interesting and individual it is."

Records kept by STT from Victoria describe a number of trees as being much taller than 100 metres in the 19th century, but the accuracy has been disputed and the trees no longer exist.

Similar historical records in Tasmania show two trees were measured at 101 metres in 1906 — it's believed they shrunk due to old age.

The second tallest tree in Tasmania is called Icarus Dream and measures about 97 metres and is located in the Styx Valley.