Neil Jenkins has backed calls from New Zealand fly-half Dan Carter for a change in World Cup regulations over the use of match balls in practice.

Carter, who missed five kicks from nine attempts in New Zealand's win over Scotland, is frustrated that the Gilbert match balls are new for each game.

England's Jonny Wilkinson also has concerns over the flight of the balls after missing two attempts at goal against Samoa.

Jenkins, the Wales kicking coach, explained that new balls do not fly as well through the air as those that have been kicked in during the week.

Wales admitted they were surprised to discover that teams would get two match balls to practice with on the day before the match with all the others to be new.

Jenkins said: "I understand where Dan is coming from. When we were told we won't get most of the match balls until the day of the game that caused a concern straight away.

"The All Blacks will tell you it is not what they do back home and it is certainly not what we do.

"We get brand new balls a week and a half before the game, or certainly on the Monday, and we kick them in and they are ready by the Wednesday or Thursday.

"I certainly think these balls should be kicked in a bit earlier than they have been. It does make a big difference come Test day. The ball travels better, the flight of the ball, everything.

"Sometimes a brand new ball doesn't fly as well as one that has been kicked in. It can cause problems if kicking is a big part of the game. '' Wilkinson found exactly that problem on his first World Cup appearance, against Samoa, and described feeling "helpless'' as two kicks drifted wide.

He said: "I don't care if I am kicking badly as long as I know it is me and I can work on it.

"The difficulty can be finding the accountability. You ask yourself, is it me or not?'. That is what affects my concentration.

"I missed a couple of kicks against Samoa and both were very heavy. They shifted quite a way, right to left, which is quite unusual for me, with no wind.

"It is a bit like playing in a wind that you can't work out, it leaves you feeling a bit helpless.

"The next kick, you are then asking yourself, do I allow for that, treat it as a one-off, or do I ignore it?' "That is the tough part, you end up playing mental games outside a game, which you don't really want to be doing.'' Gilbert promised to "re-examine the balls sent back to them by the IRB and will report should any inconsistencies be found.'' It said all balls were pre-kicked: "Whilst taking very seriously the comments made by Dan Carter and members of the New Zealand management team following the game in Scotland last weekend, Gilbert remain supremely confident in the standard of balls delivered for use in the Rugby World Cup.''