The country’s largest superannuation fund, AustralianSuper, has fallen out with Optus over the failure to deliver new mobile towers for network infrastructure the fund acquired for almost $2 billion.

The dispute, playing out in private between the Singtel-owned telecommunications giant and AustralianSuper, which manages $335 billion, comes as superannuation funds take an increasingly active role in running the assets they invest in. An extended stoush would be particularly damaging to the superannuation fund giant, which is increasingly focused on actively managing its infrastructure investments.