Kiwis' Shane Bond catches Ashraful (Getty Images)

New Zealand captain Stephen Fleming revealed how his side's "aggressive" approach had paid dividends as they thrashed Bangladesh by seven wickets to boost their hopes of reaching the Super Six stage of the World Cup.

Needing to win quickly to improve their run rate in Pool B, New Zealand easily reached their target of 199 for the loss of just three wickets with 99 balls to spare.

All-rounder Chris Cairns smashed 33 from just 21 balls to seal the victory with Scott Styris making 37 from 36 deliveries at Kimberley.

Fleming led the assault with a quickfire 32 while fellow opener Craig McMillan anchored the innings with 75.

"Craig is warming to the opening role and he really did the job and formed the basis of the innings," said Fleming.

"Our approach was to be aggressive, we wanted to get them as quickly as possible without being reckless.

"I thought Bangladesh played well and the structure of their batting was a lot better than the last time we played them."

The decision to pull out of their game in Nairobi against Kenya, which resulted in the forfeiture of four points, left the Black Caps needing to win their remaining two matches to stand a chance of qualifying for the Super Six.

And Pool B is so tight between five teams that it may well come down to run rate if points are level at the end of the group stage.

As a result fast bowler Shane Bond, who returned to form in this match with three for 33, said their game plan had been to try to bowl out Bangladesh as quickly as possible.

"It was a good batting wicket today. We were going to put them in anyway (if we had won the toss) to see if we could knock them over," said the paceman.

"The nature of one-day cricket now is that you have to try to bowl sides out. We were looking to take wickets because it may come down to run-rate."

Earlier Bangladesh opener Mohammad Ashraful posted his best-ever one-day international score of 56, off 82 balls, and his country's first World Cup half-century to help his side to 198 for seven.

Once he had departed with the score on 107 for six the Asians were put in a stranglehold by 10 overs of Daniel Vettori's tidy left-arm spin which went for just 19.

However, there were a flurry of late boundaries from Mohammad Rafique, who smashed two sixes and three fours in a run-a-ball 41, and captain Mahmud (35 not out) as the pair shared an unbroken eighth-wicket stand of 70 - a record for Bangladesh.