Until now, maps showed Mt Jackson as the tallest mountain in the territory at 3,184 metres, according to researchers at British Antarctic Survey (BAS).
However, new satellite data reveals this is not the case, with Mt Hope being 55 metres taller than Mt Jackson and 377 metres higher than previously thought, they said.
The discovery was made to update planning maps for pilots operating in Antarctica.
Previously, measurements from old overland surveys were used for mapping the region and the new high-resolution satellite measurements, accurate to within five metres, show there are several errors in these surveys.
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"As well as discovering Mt Hope is the highest mountain in the territory, we have identified several other interesting discoveries.
"These include new mountain heights, ranges in new locations by up to five kilometres and even some new peaks which had not been surveyed before," said Fox.
"Maps with reliable measurements of the highest peaks are an essential safety requirement for flight planning. Accurate elevation data from satellite imagery now allows us to produce these resources for Antarctica, where flying is difficult at the best of times," said Fox.