New Zealand has called up Otago batsman Aaron Redmond as potential cover for injured Jesse Ryder in case the burly left-handed opener is ruled out of the remainder of the Twenty20 World Cup.

Ryder, who is suffering from a groin injury, is still under observation in a hospital here while the rest of the team travelled to Nottingham. New Zealand team manager Dave Currie said the diagnosis of Ryder's injury is still unclear, but it seems likely that the batsman is suffering from a significant infection.

"He has been in considerable discomfort. In the meantime Aaron (Redmomd) joins the squad as a precautionary measure. However, any replacement will have to be approved by the ICC," Currie said.

Redmond has been playing county cricket in Lancashire and will join the squad immediately. He has played seven Tests for New Zealand and was a leading performer in the latest domestic Twenty20 competition, finishing top run scorer including an innings of 100 not out from 58 balls.

New Zealand have been plagued with injuries in the tournament with skipper Daniel Vettori nursing a shoulder injury, which forced him to sit out of the two preliminary matches the side has played so far. In-form batsman Ross Taylor is also being monitored after he strained his hamstring while pacer James Franklin is likely to play in the next stage despite a knee problem.