Spark Sport's website went offline at around 10.30am this morning - on the final day of its $60 Rugby World Cup Tournament Pass earlybird deal.

After today, punters will have to pay $80, rising to $90 for those who wait until September.

A spokesman told the Herald it was 'planned maintenance."

However, the timing is curious, and when the Herald visited it using various devices, Spark Sport was showing only a blank screen, not any planned maintenance message.

Websites typically carry out maintenance after hours.

The spokesman said the maintenance was timed to not coincide with any live sports events - though it left an NZME staffer who was trying to subscribe to the service frustrated.

The Rugby World Cup kicks off in 111 days.

Spark has stressed that its service has been in a "beta" or test phase that was always going to involve ironing out a few bugs - and that it has worked smoothly most of the time so far.

Still, users have taken to social media to sound-off about bugs that have affected Spark Sport Formula One and hockey coverage at times.