New Zealand's Tim Southee still struggling with foot injury

New Zealand are increasingly concerned that all-rounder Tim Southee's foot injury could be more serious than first expected.

Southee was injured during the third one-day international against Sri Lanka last week, when he made his return to action after being rested from the first two games.

A scan soon afterwards showed bruising, but batting coach Craig McMillan said on Saturday his absence could be longer, with Southee now sporting a moonboot and unable to practice.

"I think it might be ... a little bit," McMillan said. "It's something that will take a wee while to get right.

Live International T20 Cricket

"I'm not exactly sure of the time frame, whether it's two to three weeks, as to where he is at. The plan in place, fingers crossed, is that hopefully he'll be back for the end of the season.

"It's not that far away, but the plan is to have him back firing for the Australia series."

Southee has already been ruled out of the one-day series with Pakistan, which starts in Auckland on Friday, and he would appear unlikely to be fit for the limited-overs series with Australia which follows.

The trans-Tasman rivals then face off in a two-Test series, with the start of the first match on February 12.

But McMillan hopes New Zealand have enough bowling options to cope without Southee, if the injury should keep him out for the rest of their season.

"It's reassuring to have those options," McMillan said. "One of the great things from this series [against Sri Lanka] has been the form of Matt Henry [he took 13 wickets at 9.38]. That shows a confidence to come into the set-up and perform straight away."