"There are plenty of offers out there that weren't around years ago," he said. "But yeah, at the moment it's concentrate on playing for New Zealand and giving that everything at the moment."

It won't affect the team, he said: "We've seen a number of guys who haven't taken contracts, guys that are sitting on this plane with guys with contracts."

Among the players who have refused contracts in recent months are Kane Williamson, Trent Boult, Lockie Ferguson, and Adam Milne. Of them, Williamson is in the squad for the Afghanistan Test, which will be the first of six Tests in the subcontinent (with two in Sri Lanka and two in India to follow), after which New Zealand will host England at home in November-December.

"If you look at it as a whole - six Test matches in the subcontinent - it's exciting," Southee said. "It's probably something we haven't done, in my time anyway. It's a great challenge for the side."

First up: Afghanistan.

"They are still new to the red-ball format, but we've seen in the other formats what a side they can be," Southee said. "Just recently in the T20 World Cup, last year in the one-day World Cup [where Afghanistan finished sixth], they are an improving side. They've had great success in those two formats, and I am sure as a country they want to have success in the longer format as well.

"Every time we have come up against them in a world event in the last five or six years, we know they are an improving side and a dangerous side. Especially in their part of the world. We just saw them making the semi-finals of the T20 World Cup, a couple of upsets last year, and the one-day World Cup as well. So we know they are a very good side in those conditions."

"That part of the world, spin is going to play a big part. They've got some quality spinners, mixed in with some quality quicks as well," Southee said. "We've seen in other formats that's been their strength, their bowling unit, particularly their spinners. It's going to be an exciting challenge.

"[The role of the spinners] might change from venue to venue, change from India to Sri Lanka and back to India. We have the options. We have guys that can bowl spin, offspin, left-arm spin, so we've got a good mix, mixed in with some quality pace as well. It's exciting for all the spinners. We were in Bangladesh last year, so as a spin bowler, I'm sure you're looking forward to this challenge."

The Test against Afghanistan will be played from September 9 to 13 after which New Zealand will travel to Sri Lanka before returning to India.