Hamilton - British and Irish Lions coach Warren Gatland has accused New Zealand players of illegal blocking and urged officials to clamp down on the tactic in this week's first Test against the All Blacks.
Gatland said off-the-ball obstruction was endemic in New Zealand rugby and his players had been blocked throughout their five warm-up games, costing them valuable attacking opportunities.
The New Zealander made his comments ahead of the Lions match against Waikato Chiefs on Tuesday but they were aimed squarely at Jaco Peyper, the South African referee in charge of Saturday's first Test at Eden Park.
"The frustrating thing for us is the amount of blocking that's going on, the off-the-ball stuff," Gatland told reporters.
"It makes it difficult to complete attacking opportunities and situations because there is so much happening off the ball in terms of holding players.
"We've raised it with the referee already. If you listen to the referee's mic, they were talking about it constantly through the Maori game. They gave a couple of penalties for blocking.
"It's one of the hardest things to pick up because it tends to happen quite a long way off the ball."
Gatland said the blocking impeded his players' ability to compete in the air, nullifying the Lions kicking game and costing them tries.
He said officials stopped the tactic in the Maori All Blacks match last Saturday, coinciding with the Lions' best performance on tour so far in a 32-10 win.
But he said such shepherding was often difficult to spot and warned "we'll keep raising it".
"When you go back and look at the tapes and look at all the stuff off the ball, where someone's run a line or stopped someone getting through, some of it is very subtle," he said.
"That's made it difficult. It's part of the game in New Zealand, all New Zealand teams are doing it at the moment... we've just got to hope the referees, assistant referees and the TMOs pick up what's going on."
Gatland's allegations are sure to raise hackles in the All Blacks' camp, particularly after he said New Zealand coach Steve Hansen was "worried" about the improving Lions.
Hansen has been firing barbs of his own in the lead-up to the Test, accusing Gatland of having only one style of play and claiming inside knowledge of the Lions reinforcements.