Spark Sport costs $24.99 per month (with some Spark mobile and broadband customers able to claim a $5 rebate), while Sky Sport now costs $49.99 per month (although it can fall to $24.92 per month if a customer pays $299 to commit to a 12-month bundle). That means someone who buys both services together will save up to $25 per month.

Spark said the bundle would only be available to any broadband or mobile customer on contract. It won't be available for those on pre-pay.

The initial period of the deal is six months.

Neither side would comment on commercial terms.

At this stage, Sky is not offering a Spark Sport bundle for its customers.

No-one had been picking that the two competing sports streaming services would be offered in a single bundle.

But it's not the first time Spark and Sky have cooperated.

Spark offered Sky's earlier sports streaming service, Fanpass, to its own customers at a cutprice rate under a wholesale deal.

Sky hosted a 2019 Rugby World Cup channel for its commercial customers, providing Spark with an at-cost way provide pubs and clubs with easy access to the tournament.

After Sky bought entertainment streaming service Lightbox from Spark for $6m, the telco's qualifying customers still got free access under a wholesale deal for six months until June this year, when Lightbox was merged into Sky's Neon.

And, recently, Sky boss Martin Stewart said he was open to Spark Sport available on Sky's new box, which will feature Netflix and other third-party apps.

In other areas, head-to-head competition continues - or is even expanding.

Meanwhile, Sky is planning a push onto Spark's home turf with a Sky Broadband service - now in testing - slated for commercial launch next year, with mobile service to follow.

And Spark, for its part, has recently expanded Spark Sport into pay-per-view boxing. The company has partnered with Duco Events and NZ Herald publisher NZME on the next Joseph Parker bout.

Sky was down 1.94 per cent to 15.2c in early trading. The stock is down 70.1 per cent for the year, outpacing the broader market's 0.77 per cent fall.

Spark was trading flat at $4.62.