Opening bowler Trent Boult has been ruled out of New Zealand's second test against Pakistan after feeling discomfort in his right knee during training, the team said on Thursday.

The left-arm pace bowler appeared to injure his knee while fielding during the first test in Christchurch, won by New Zealand by eight wickets, but coach Mike Hesson said he had been suffering from irritation in the joint for several weeks.

"Trent has had a minor discomfort in his knee dating back to the tour of India, which we've been managing in recent weeks," Hesson said in a statement on Thursday.

"Unfortunately he irritated it further while fielding in the first test. He bowled again and we were optimistic he would be ready for Hamilton, but during training on Wednesday felt further pain and has subsequently been ruled out of the test."

Hesson was still hopeful Boult would be available for their one-day series in Australia in early December, but said he would monitor his progress over the next few days before making a decision.

All-rounder Doug Bracewell has joined the squad in Hamilton, with the second test due to begin on Friday.