A new trans-Tasman undersea cable is set to go ahead early next year.

The Tasman Global Alliance Cable is a joint-venture between Spark, Vodafone, and Telstra in Australia.

It hit a snag in August when it was reported Telstra had pulled out, but the three today have announced a $91 million investment to move the project forward.

The cable will provide an alternative to the existing Southern Cross Tasman cable for telecommunications traffic.

It'll run between Raglan, and Oxford Falls in Sydney.